I had the most vivid dreams when I was little, full of detail-rich landscapes, buildings, etc. I was certain when I woke up that these had been real places. I was always experiencing the dream as the subject of it - never just watching. Eventually I accepted that these were memories. I never figured out where most of the places were, but one came back to me clear as day when I saw it in a National Geographic a decade and a half later. We should encourage kids to journal all this stuff.