A chrome tubular rail. This was about half a mile down a gated-off fire road, usually closed to traffic, with no sign of a crash or any other pieces nearby. I would guess it's a crash bar for a cruiser type motorcycle, and it fell off a cop bike. I carried it about two miles to the next available garbage can.

Note MTB, light, bell, slicks, platform pedals, kickstand, but also suspension fork, no fenders... part-timer :-D