Mike Caldwell begins minting Casascius physical bitcoins -- brass, silver, and gold-plated coins with a hidden private key embedded under a tamper-evident hologram. Each coin was pre-loaded with BTC, creating a tangible way to hold and trade bitcoin in the physical world. The coins became iconic collector's items in Bitcoin culture. In November 2013, FinCEN contacted Caldwell and classified his operation as money transmission, forcing him to stop selling funded coins. Unfunded Casascius coins remain highly prized collectibles.
Bitcoin Wiki: Casascius Physical Bitcoins