Here are Florida Fish and wildlife Conservation Commissions (FWC) rules and regulations about collecting aquarium fish, live rock and coral. And it plainly says "The harvest of live-rock, substrate with living organisms attached, is illegal unless harvested at a licensed aquaculture area."
Florida Coral Rules and Regulations
Marine Life and Tropical Ornamentals
Recreational Harvest of Marine Life (Aquarium) Species
For stony corals, fire corals and sea fans any collection is prohibited and the collection of black corals and other octocoral species is restricted. Also you can only collect live rock from a licensed aquaculture area. So picking live rock up from a rock anywhere is illegal
The rules on aquarium fish are pretty lax. You need a fishing license and there are size requirements for certain species of fish and you are limited to certain number of fish per person per day. There are also gear restrictions to keep in mind.
These rules and regulations are there to protect these precious resources. As someone who lives in Florida and getting a Masters in Marine Biology, it think it is our job to use our knowledge of reefs and their inhabitants to educate those that are clueless. It is also our responsibility to practice our amazing hobby in a way that will protect and preserve our reefs.
If you really want to collect something from Florida, collect a Lionfish. They are a menace here and ruining our reefs.