I found this pod a couple of weeks ago on the seafront in Sarasota. I just could not identify it, however after my visit to the library I have found out that it is the pod of the one of the albizia trees, albizia lebbeck. The delicate pods are about 6 to 8 inches long, flattened and papery and they rattle. I am sure I don't need to explain the origin of the name to you, do I!
There are many other albizias some with longer curling pods which is why I had difficulty finding this one in the guide book. It is, apparently, a very naughty and invasive tree ( category one!) here in Florida, wantonly seeding everywhere and its lovely pods even described as "trashy"by one commentator. The flowers are pretty, very fragrant pompom affairs, all in all a very girly plant, chatty, decorative and just a tiny bit louche!..