Hey Tre, I thought you were seeing them driving down the road, assumption being ditches not in people's yards. Of course no one should go digging in somebody else's yard. You need to stop and ask for a cutting of the plant if you want one. The few times I have seen plants growing on private property that I wanted seed of or a cutting, I stopped and asked. *The people were ever so gracious and I recall one man who actually sat and bagged seed for me so that I could share it with friends. Penstemon, I got Smooth Penstemon that had been growing as a remnant along the side of his house that he never mowed. I told him what it was and he was very happy. Next year I brought him some seedlings I had grown from his seed. He was thrilled. Now he has my phone number and even his wife called me to come and look at something. Turns out it was garlic mustard but they still called. I have met some of the nicest people the few times I have stopped. *
Hibiscus is a member of the Malvaceous Family.
I googled this and found that your plant, if it looks similar to the image you linked to only in white, might be a hybrid of the native species and the introduced species- Malvaviscus arboreus penduliflorus Alba
I found it here-
There is a native version that is being referred to as Turk's Cap Mallow that is white but the leaves are somewhat different.
I am not all that familiar with plants that are indigenous or that have naturalized at the expense of native flora and fauna in Forida. You may need to get a hold of a native plant society down by you and ask for help on the ID but take a photo with your own camera if at all possible so that the leaf and flower to the exact plant you want identified will be able to be seen by people trying to help you. So many look so much alike it isn't even funny. *Incredibly frustrating though.
They are definitely not sterile. Many hybrids have been released that were thought to be sterile that definitely weren't. *Classic example is the Bradford Pear. Once they began introducing more Caleryana cultivars to the market, they began hybridizing wildly. The offspring were anything but sterile.
Best wishes to you.