Ghosts.

When I was a student, I moved into an ancient cottage in East Kent (UK) - Crockshard Cottage.  Very isolated. I was sharing the rent with another student, Roger. The first night I slept there, Roger was away. I was alone. I went to bed. Every now and then, a car would pass by, briefly illuminating the room through the feeble curtains. In the middle of the night, I awoke, or so it seemed, to see an old man sitting on the chair by the window as a car passed by. A more impressionable person would have reported seeing a ghost. Waking up fully, he disappeared.

Again at Crockshard Cottage, I had a dream of the cottage in what seemed like Victorian times.  Children playing in the garden. A woman hanging out clothes on the line. The cottage lacked the extension that had recently been built.

The cottage had a cellar. In another dream, I went down to it and had the (apparent) realisation that I had murdered someone and had buried them there, and had repressed the recollection for my own psychological survival.