Disclaimer: Consuming wild-harvested foods always carries a risk of misidentification that could result in serious injury or death, even with the advice of a professional, but especially without it. Anyone choosing to do so does so at their own risk.
As it happens, when my fellow English majors were taking Underwater Basket Weaving for their electives, I took a bunch of upper-division science courses, including Mycology. There's a saying among wild mushroom enthusiasts: "There are two kinds of foragers: adventurous ones, and old ones." I have taken great pains to be one of the latter.
My advice would be to first take a spore print. Lay a piece of plain white printer paper on a dinner plate and put your sample, gills down, on it. Put a bowl over it, put it in the fridge, and leave it undisturbed at least overnight. The spores will collect on the paper; the color of the spore print is often useful in keying out mushrooms.
I'd then email pictures of the mushroom and spore print, along with a description of the medium it was growing on and any other relevant details to a professional. Although several come to mind, I'd probably start with Dr. James Kimbrough at the University of Florida. One of the big challenges for mushrooming enthusiasts in Miami is how radically different a climate we have; a lot of the stuff that grows elsewhere doesn't occur here, and a lot of the stuff that grows here isn't found elsewhere. Dr. Kimbrough really knows his stuff, and has written at least one book that I know of dealing specifically with mushrooms of Florida.
One last word of advice: if you're going to harvest and eat wild mushrooms, pay careful attention to spoilage. A lot of people fall prey to what they think is mushroom poisoning, but actually turns out to be food poisoning (which, by the way, can also be fatal) from eating mushrooms that are past their prime