I found this small spring while cleaning my car yesterday after a 1500 mile roadtrip. It was laying on the driver's side floormat, down in the corner by the E-brake. Pencil is for scale.

Is it from the car? I don't think it's from any of the gear I brought with me.

 

Looks like it might be the spring for the rear, upper, hatch receiver. Seems a tad small, but it might be that. Found inside the white portion and has the silver pin holding it all together.

 

^Nope^ Just checked.

It may have come in on my shoe, but the ones I brought on the trip didn't have much tread, so I think that's unlikely.