Little brass thingy

[alabamajoe]

Not sure what it is but appears to be brass. Any ideas?

 

[bradyboy]

bullet from an air gun?
cant think of the term used
Brady

 

[traderoftreasures]

looks like part of a rivet

 

[vayank54]

Is there a hole through the center of it in the first pic? If so it's a modern button with a selfshank. It's smashed though. If not I don't know