2010 MCS. This was on the trunk floor. Not sure if it unscrewed from something or where it came from. It is spring loaded. Does this **** look familiar? Thanks...

 

LaurelEdition, your post needs a picture of the "****". If you hadn't said "spring loaded" I would have ventured a guess on the cigarrette lighter blank (which is black) and is used to cover the hole for the 12volt connection in the back. I'm thinking maybe this piece you saw might be related to the upper boot handles? Did you carry anything else back there that came apart maybe. Please post a picture soon.
I shouldn't try to answer posts before my morning coffee... :0

 

Resolved. The part was from a tool. Somehow unscrewed. I had pictures posted but deleted them. I thought I deleted my thread also. Anyway, thanks for your time...