Found this in my yard in SE Wisconsin about a foot deep. Feels heavy for its size, but I accidently scarred the edge with my shovel and it appears to be solid copper.
http://www.treasurenet.com/forums/today-s-finds/129494-not-real-sure-what.html?fbclid=IwAR0dnq9sMvPlU3KYuvNsF3i-L7lD5AOgqADS_PxdzF8Mav3Z7Jjc1DMaihs
This old post has the same exact monogram, but mine is slightly larger and possibly slightly thinner. A nickel is almost exactly the same size as the small circle in the middle of mine.