On commutes/tours over the years:

Multiple license plates (two Texas, one Missouri), a non-disposable plastic drink bottle, CDs, bungee cords (used to find these on highways in Indiana all the time, not so much here in Texas), more gloves than I can count, a bicycle tail-light (a few days after a big triathlon in my area), a plug nickel, a Chicago Cubs cap, a destroyed GMRS handheld radio, diapers (a few years ago someone was dumping a lot of them alongside the road in my area), a crescent wrench and a regular wrench, a William Faulkner novel (actually this was thrown at me from a vehicle window), and a wallet with twenties packed in it and scattered on the ground around it (which I reunited with its grateful owner).