Thanks for the reply JC. The dimensions are approx 2 1/4 inches wide at the top, 1 3/4 inch at the bottom and, 1/2 inch thick. Doesn't appear to be threaded but it's hard to say for sure due to the "crust". For what it's worth, there was a huge blob of iron on the bottom of this piece but I chipped it away to get to the most defined portion.
I should have said that the relics that I've found on this site are military relics! Two tnet members thought that a few of the buttons that I found might possibly pre-date the Civil War. Every single bullet that I've found is of the round ball variety....no ringers.
Sure hope this helps.