Is this a button?

[Kapidr]

Found this detecting on the SE coast of US. Can anyone tell me if it's of any importance? I believe it's a very old button? It weighs 3.87 grams and in the last photo it is sitting on a dime to show size.

 

[Iron Patch]

I think the fact it appears to be corroding white metal suggests fairly modern. It doesn't look like an early lead or pewter button to me.