Does anybody know what these are? After taking my car for an oil change, I see them on both driver and passenger floor. I now have 7 pieces of them.

 

it could be the nut holding up some front seat related trim. if you look behind your front seats (somewhere above where the rear passengers toes would be, some part of the seat trim goes under the seat, this i think helps hold it up. Not sure as i have collected about 3 of them. Usually happens after a track day or an aggressive mountain run

 

They look like the retaining nuts that hold the carpet in place under the front dashboard. Mine keep coming loose every few months or so no matter how tight I get them.

 

Ahh, I will go take a look at it!