Check out this story in the local paper, the St. Augustine Record:

A corroded uniform button found in the mud off the St. Augustine Beach pier could be the “smoking gun” that leads to identifying a mystery shipwreck.
And the copper coin with a face of what could be Britain’s King George found by a Lighthouse Archaeological Maritime Program volunteer just adds to evidence that the wreck could be part of a British Revolutionary War fleet that fled Charleston in 1782.

Read the entire story, but note that at the time it was printed we has misinterpreted the button as having a “74” on it. It is actually a 71, but the significance is the same–the 71st Regiment was stationed in Charleston and evacuated on the last fleet to leave the city, the same fleet that lost 16 ships on the St. Augustine bar on December 31st, 1782.