Some kind of tool holder spring?

[pritch]

I went junkyardin' today and saw this:



For scale:



There was a Phillips head bolt through the center of this little dimple just below the door strike (that I never had noticed before on my truck) that held it on:



I figured it was stock, because it has some of the yellow that the truck in the JY was.

Maybe they are common, but I had never seen one before.