Hi; BigCypresshunter nailed it for you ok.
From his Link:
1798-1826
MEDIUM:
Lead, bronze, brass, pewter, silver
DIMENSIONS:
largest: 1 in. ( 2.5 cm )
MARKS:
stamped: (1), on front, inside scroll: "E PLURIBUS UNUM" ; at top: "U.S.I."; at bottom: "REGT" (silver-plated officer's coat button, U.S. Infantry) stamped: (2), front: "ARTILLERY/ REGT" (Artillery Militia, 1826; eagle and cannon design; coat) stamped:
PEACE:RONB