I did a lot of reading when I was young, and took a fancy to some of the sillier authors and poets like Edward Lear and Lewis Carroll — and I have some of their work memorized.
I myself have been writing for years. Decades. I have written poems, stories, other random things — so much so that I don’t remember all of what I’ve written.
The other day (maybe a month or two ago) one of my poems was knocking around in my head — and I was confused about whether it was something that I had written, or whether it was written by someone else. I found myself googling words from my own poem to find out who the author was. When no results came up, I concluded that it must be mine. I subsequently got my writing site functional and found it (Death of a Student).
Kind of crazy.