I know they are some sort of nail, but I had one in my tire and at the store found a near identical one and now I'm beginning to think my tire guy is playing shell games. I mean, what are the odds?
Looks to me like a self tapping screw which had its head broken off / worn down. You probably just picked them both up from the same spot, double check your driveway / lot
My vote is self-tapping sheet metal screw that had the end cut off because it was sticking too far into whatever it was screwed into.
Only the part of the screw that touches the two (or more) pieces of sheet metal actual does anything.
Person should have used a rivet.
Could easily have been stuck in the tire and then ground down on the road.
Let us help you identify that mysterious object you’ve found.
Currently in CHALLENGE mode: If you've got something obscure knocking about, post a picture, and let's see how we do. Please prefix such posts with "CHALLENGE:" so we know we've got a fighting chance.