I got a return email from Ruth Baumgardner, who clarified that the plant she spoke of on Saturday is Cassia marilandica. I think the best (brief) description on line is probably at Cornell,
www.gardening.cornell.edu/homegardening/scenee9ef.html, where I also found this photo.
A couple of notes: I'm not sure if it's going to tolerate the heat in Georgia, based upon the Cornell description. Second, it appears as though there might be some tendency toward invasiveness. That doesn't necessarily rule a plant out in my book, but definitely means a bit of caution if you're not on top of it.
