This is a Anglo-Saxon style of annular brooch called a Quoit Brooch, based on the Sarre Brooch from Kent, England, which is now at the British Museum.

This style of brooch has a separate bronze pin. Just pull the material through the center of the brooch and use the pin to secure the cloth in place.

Cast in bronze, this brooch is also available with a silver-plated or blackened silver-plated finish.

Measures 3-1/4" (8.2 cm) in diameter