Carl,
Pierced coins are fairly common in the Pacific Northwest from the late 18th century up at least to the 1860s or so. I don't recall pierced buttons, but they may well exist. They were used as ornaments. Some are US coins, many are foreign, especially Spanish colonial. I don't know of common finds in the late 19th or 20th centuries, but others may.
Best wishes,
Bob Keeler