Tiny button

I dug this small button today and quickly tossed it into my bag thinking it was some sort of tack or rivet. Once I got home and removed some dirt, I was glad to see that it was something a bit more interesting.

I'm wondering if anyone can help me estimate the age of this tiny button and also give me an idea of where it would be worn.

For what it's worth, it was found at a site where several early buttons have turned up.

Thanks!