Things I picked up:

Last year, a working bike pump that apparently fell off during someone's commute.

At the Zion century last month: a string of ruby red glass beads, probably a bracelet.

Things I've left:

dead bunny, lots of cans, badminton racquet, NAILS, the NAILS, Clif Bar wrappers, dirty diapers , car parts, a sock, a shoe, a perfectly good-looking sweater...