Mississippian copper plates
Mississippian copper plates, or plaques, are plain and repousséd plates of beaten copper crafted by peoples of the various regional expressions of the Mississippian culture between 800 and 1600 CE. They have been found as artifacts in archaeological sites in the American Midwest and Southeast. The plates, found as far afield as Florida, Georgia, Illinois, Mississippi, Oklahoma, Tennessee, and Wisconsin, were instrumental in the development of the archaeological concept known as the Southeastern Ceremonial Complex.
Source: Wikipedia — Mississippian copper plates (CC BY-SA 4.0)