Back when we had the old Victorian house, we found that in its history that it was a rooming house in the late 30s/early 40s. We discovered an old envelope tucked in the back panel of a wall cabinet we were removing that was hand written on the front in pencil “March rent”. Inside was a crisp 1936 $10 bill.
We still have it.
No idea why it was still there, can only imagine something happened to the person who put it there and it was never discovered after they were gone.