Sometimes when I dream, I remember things in the dream. I don't know where the memories come from, because they are definitely not waking memories. I don't think they are memories from other dreams, at least not dreams I can remember. Here's an example:

About a week ago, I had dream where I was talking to a girl named Sylwia on the phone. After talking to her for a while without knowing who she was, I remembered her. She was an orphan who I had promised to help. When I woke up, I had no recollection of ever dreaming of her before.

Are these memories from dreams I don't remember?