Where do dreams come from?

Dreams come from the unconscious self (excluding any metaphysical realities from above or below, which may very well interact with the personal unconscious in a myriad of ways). They are the psyches' way of healing itself.

The unconscious is mostly theorized to be found within the “reptilian” parts of the brain, or those parts of the brain which evolved earlier than our other parts and therefore is theorized to contain our most primal drives and desires, as well as the limbic parts which evolved in a hunter-gatherer context and are theorized to be the seat of our emotions.

These areas include parts of the brain like the pineal gland, the brain stem, the cerebellum, the pons, medulla, etc. These parts of the brain conflict with the neocortex and the prefrontal cortex in particular–one of the most recent parts of our brain to have developed–which is responsible for reason, delaying gratification, and regulating moral norms (one could situate a lot of Freud’s superego here–although Freud himself took a more “the whole is greater than the sum of its parts” in respect to locating precise areas of the brain with the parts of his tripartite consciousness).