There's plenty of treasure to be found in Florida, but the way you go about it is tricky.
Most public, county run beaches allow for metal detecting on the dry sand. State Parks don't allow any metal detectors. (maybe by exception)
But here's the real kicker, at least in Walton County, it's "illegal" to metal detect in the surf. Because it's considered under water and those rules of engagement are very strict and highly regulated.

But this last one is worse than the "real kicker".
The State of Florida has a law that roughly states that any artifact that you recover that's older than 50 years old, it is by proxy state property and must be turned in to some gubment authority.

So here's what the State has decided to leave for you to scavenge up after you turn in the Pieces of eight and the civil war musket you found.

You may metal detect the dry sandy beach, that's considered "customary use". You may keep any gold or silver that you find, or you may try to find it's original owner. But they're probably gone by now.

You see lot's of people visit the Florida beaches and lot's of people lose their jewelry "on the beach"!!. And we're talking frequently.
There's all kinds of gold watches, necklaces, rings and other jewelry just sitting slightly below the surface of the sand. Honestly, one nice gold necklace will probably get you more than a day running a dredge in an Alabama river. (Props to my Alabama peeps)

So YES! You can prospect in Florida, just be aware of the possible downsides.

Cheers,
Dave