Coilygirl, looks to me like a lead washer. They used them back in the day and even now days for some applications, although the opening on yours seems a little small.
This is much thicker than a washer thrillathahunt and the same patina as lead bullets I've found that have been in the ground a long time.Still you might be right just a washer.Thanks for your input. I wondered if it might be carved lead for checkers or chess but why the hole? Shrug.
Nokta FoRs Gold, a Gold Cube, 2 Keene Sluices and Lord only knows how many pans....not to mention a load of other gear my wife still doesn't know about!