That's fascinating! I haven't thought about this before, that some of my memories might be dream memories and not "real". I have noticed that sometimes I'll remember things while dreaming that didn't happen in real life, so where did they happen?

I had a dream last night were I remembered being on a street and having previous experiences there. But I've never actually been on that street. Did I have those experiences in another dream? That suggests a continuity between some dreams, a continuing story connected by memory, rather than the disjointed, random experiences we assume dreams are.

Or maybe the memory was "planted" instead, like in @churdtzu's ayahuasca trip. How mind-blowing, that a memory could come into existence and feel completely real with no "actual" experience to create it. It calls all memories into question and makes you wonder if you might have just appeared in this world a second ago, with all your memories born in that moment with you.