I think it is brass......dont know what it is but it looks like a pocket watch but also looks like a side portion of an old fishing reel with a brass nut showing. I have dug brass that still has a dull sheen.
your everyday person wanting to cash in their change just are not all aware of what a silver rosie is, and the merc probably looks like foreign or play money to them.....we though, are not your average people.
On your own property at that.....can't get any more convenient. All of your buttons are great, i like finding old lathe turned bone buttons, they can be earlier than CW. Your white porcelain buttons are called Prosser buttons and are post 1840.
Awesome silvers...I like your progressive photos of the dirt slowly making its way off the coin. We all like to go through those steps slowly as we take it all in, especially when we know it's a good one under the clod.