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