According to Florida's Fabulous Treasures . . .
" in Boca Grande Pass on the north end of Cayo Costa an American frigate with $3,000,000 in minted U.S. gold coins sank in 1823.
• There were reports that when they were first dredging the Venice Inlet, a shipwreck was struck with the clam bucket dredge and gold coins were being picked up from the sand piles. A scan of old newspapers might confirm this story.
• After tropical storms, Spanish coins have been washing up on the beach at Stump Pass, just SW of Grove City. The dates are running from l754-l762, and the coins are in good condition. A gold 8 Escudo with a similar date was recovered in the water from the same area.
• Spanish gold coins were found on the beach at Longboat Key near Sarasota, after a dredger pumped in sand from off-shore.
I haven't found any of these gold and silver coins myself . . .