Some Cayce quotes to get you started:
… for dreams are that of which the subconscious is made, for any conditions ever becoming reality is first dreamed. (136-7)
… for such experiences as dreams, visions and the like, are but the ACTIVITIES in the unseen world of the real self of an entity…
(Q) What state or trend of development is indicated if an individual does not remember dreams?
(A) The negligence of its associations, both physical, mental and spiritual. Indicates a very negligible personage! (5754-3)
In dreams, visions and experiences, each individual soul passes through or reviews or sees as from a different attitude those experiences of its own activities. And these are, in dreams or visions, as emblematical conditions in the experience of that soul-entity. At others [other dreams] we may find the activity of the body-physical regarding the diet or the activities in any experience of the mental body. (257-136)
Dreams, with their import in the experience of individuals, are – as we have indicated – experiences of the soul or cosmic body in periods when the consciousness of material things is more or less subjugated to the mental or spiritual forces of an entity. And these come either as lessons, forewarnings, or emblematical experiences that may be applicable in the experience [of] the one having them – or those associated. (294-159)
Each and every soul leaves the body as it rests in sleep. (853-8)
… dreams are the correlation of various phases of the mentality of the individual, see? … expressions that bring from one subconscious to another those of actual existent conditions, either direct or indirect, to be acted upon or that are ever present, see?
Hence we find visions of the past, visions of the present, visions of the future. For to the subconscious there is no past or future – all present. (136-54)
More credence, more attention should be given to the impressions the body receives while in the sleeping state, for the subconscious forces, the soul itself is being builded. (758-27)
(Q) Why in early childhood did I dream so many times that the world was being destroyed, always seeing a black destructive cloud?
(A) From the experience in the Atlantean land, when there were those destructive forces as indicated. The entity saw or lived through those experiences of at least two, yea three, of the destructive periods; saw the land breaking up, as it were. (823-1)
The dreams again and again present to the entity those lessons, those truths, that the entity seeks to apply in the life, and as these are presented may the entity take those warnings and those lessons from same, and applying same in the life brings about those things that bring more peace, more satisfaction, and a better understanding of the conditions, the purposes, and all of life – for it is not all of life to live, nor yet all of death to die. (136-62)
The dreams are that, that the entity may gain the more perfect understanding and knowledge of those forces that go to make up the real existence – what it's all about and what it's good for – if the entity would but comprehend the conditions being manifest before same. For as the visions in dream are presented, the inner forces of the entity, in no uncertain way, are presenting emblematical conditions to the entity for its study and for its good, see? (140-6)
DREAMS are such of which buildings come into the material aspects of life. First as visions that are as to some visionary, unreal. They are crystallized in the lives and activities of others through those constant actions upon the various elements in the body of an individual entity, which is as being studied. Then they act upon those in such a manner as to bring into being realities … (262-8)
DREAM is but ATTUNING an individual mind to those individual storehouses of experience that has been set in motion. Hence at times there may be the perfect connection, at others there may be the static of interference by inability of coordinating the own thought to the experience or actuality or fact set in motion. Hence those experiences that are visioned are not only as has been given to some, to be interpreters of the unseen, but to others dreams or as dreamer of dreams, to others as prophecy, to others healing, to others exhortation, to this and that and the other; yet all are of the same spirit. (262-83)
(Q) What is meant in my life reading by the statement that I would have imposing dreams and how can I best interpret them to be helpful to me in the present?
(A) These have come, these may come. Ye interpret them in thyself. Not by dream book, not by what others say, but dreams are presented in symbols, in signs. Oft they may be as opposite that which is presented to the body which has been in some of those indicated that bring warnings, blessings. Then keep thyself pure in mind and body. For the Lord's are oft spoken in dreams, in visions. For He is the same yesterday, today and forever. Be not unmindful that there is the manner of life ye live so that ye merit this or that experience. (1968-100
First, there are dreams that are produced by conditions of the digestive system of a physical body… Then, there are those manifestations that come as the correlation of mental forces in a physical body to the mental forces of other bodies and conditions… Then, there are the relations of the mental with those of the spiritual conditions of an entity, from which the mental of a living physical entity may gain impressions. From the first condition as given, little credence may be given, save as to the physical condition of the entity gaining such impressions, for these are in reality dreams. The second are such as those who receive such impressions would do well to study. As has been given, many receive such impressions, and might be benefited physically, mentally and spiritually by following or adhering to many lessons as are given through such impressions. In the third we find many conditions wherein moral, physical, mental and spiritual aid is obtained for self and for others. (900-13)
Yes, we have the body, the enquiring mind, Edgar Cayce. This we have had before, with the dreams that come to the body from time to time. These [dreams], as we see, are emblematical of the way and manner in which the physical conditions are to be brought about in the operations of the work being attempted; for these are dreams: The correlation of subconscious forces with OTHER subconscious minds and entities who are related directly and indirectly with the operations of same. (294-62)
Dreams (for this body has many) come through the various channels as we have given respecting dreams. Dreams or visions are the subconscious forces of an entity while the conscious forces are subjugated, and the experience for the mind of the soul (or the subconscious) is often tempered by the physical or mental experiences of the body, and when such is the case these then are presented often in emblematical ways and manners. Dreams are as other mental conditions of the threefold nature,  experiences of correlation of conditions in the mental body, or  correlation of experiences of the mental or physical body, with the experiences of the subconscious forces of the body, or  the reaction from physical conditions existent in the body. One should, then, in interpreting dreams, be aware of that causing such conditions, through same make the differentiation, that the experience may be applied in the daily life; for only through experience does an entity or being develop; for little may be learned save by experience of the mental or a phase of the mental forces of a body, or through same. (302-3)
Now, as respecting dreams and their relations with the physical mind and the action of the body respecting same, the entity – the body – should first gain that proper conception of that that takes place in vision or in dream; for there are variations in that seen or experienced while in the subconscious or in the sleeping state by the body.  There are those that are of the purely physical nature – the reaction of properties taken in the system when digestion is not in keeping with assimilations, and then one experiences those conditions that may be called nightmares.  Then there is the mental condition of the body wherein worry, trouble, or any unusual action of the mind – mentally – physically – [causes] seeking for the way and manner of understanding. This may bring either the action of the subconscious with the mental abilities of the body, or it may bring wholly correlations of material sensuous conditions. These may appear in the form of visions that are in a manner the key to the situations, or they may appear in conditions as warnings, taking on conditions that are as illustrations or experiences.  Then there is the action of the purely subconscious forces, giving as lessons to the body out of its own experiences. These are phenomena, or experiences for a body to use, to apply, in its everyday walk of life, just as experiences of the mental condition of body may bring the better understanding of conditions to the whole body. (4167-1)