Things in dreams not related to your waking life

I know this can fit into many smaller topics, but I find it more interesting to lump it all into one.

Does anyone know why it is that select things pop into our dreams, which we arent thinking about in our waking life or dont exist?

For example, last night I had a dream where someone was performing a scene from A Midsummer Nights Dream. In my waking life, I have never read that play. I have never seen it performed, nor have I seen a movie of it. When I woke up, I had to Google it just to find out what its about. Yet in the dream, I dont remember any of the scene performed, but in my mind during the dream, I knew it was from that play.

Another example would be that I had a dream where me and my mom were going shopping. We drove into a shopping center parking lot that to my knowledge in reality doesnt exist. As you drive in, there is a Wendys. In the dream, once we passed the Wendys it trigger a memory. In the memory we were about to go to see a movie in that shopping center, but decided to eat at the Applebees first. From our seat in Applebees, I was able to look out and see the Wendys that we just passed. This triggered memory did not occur in my waking life.

A last example would be songs. For example, in one of my dreams last night, the song Wheel In The Sky by Journey was playing. However, it was a studio recorded duet between Steve Perry and someone else. I has to have been months since I have heard that song. And to my knowledge, this recording doesnt exist.

Any ideas as to why our mind makes up memories that never happened? Is there any way to make any sense of these types of occurrences?

I don't think we dream of any things without any knowledge about it.

Probably we've seen or heard that thing briefly when we were awake. Probably you heard someone talking about A Midsummer Night's Dream but you forgot about it, and it was left in the deeper parts of your memory. And I believe dreams have a tendency to jumble sequence up, probably cause there's no sequence or order in our dream world.

I used to dream about the building I lived at when I was young, and there always seem to be a hidden passage linking floor ? to floor 1. But in reality, that hidden passage obviously doesn't exist.

I believe that everything in your dream comes from some part of your waking life. I agree with carrot about your fist dream.

I can relate to your second dream. I often think that I'm having a memory in a dream, but upon awakening I realize that it never occurred. I think it may be because we have memories of other dreams while we are dreaming that we may not even remember consciously.

I think your third dream can be explained by taking and mixing concepts together. Steve parry may have not really done a duet with somebody to Wheel in the Sky, but you have heard the song and know who Steve Perry is. Your mind added these concepts together and you got your dream. I don't believe that there are any real concepts that aren't taken from commonalities of real life. You can dream of green monkeys because you have seen monkeys and things that are green in real life, although pink monkeys do not exist. In a dream your mind has to make up everything that you are seeing. Some of it will be strange combination's and won't make sense.