I had one of those come up in my shrub boarder last year. Dame's Rocket for sure. It smells wonderful in the evening, like the sweetest Stock! I guess it might be a pest some places, but even though I let it go to seed, it never came back. We are pretty hot and dry here, so maybe it needs more moisture. I'd take it over Cats Ear and Bindweed any day. This post was edited by BarbJP on Tue, Jun 10, 14 at 0:17

Thank you for the caution, well received, but this sample was brought to me for identification by a young friend who found it growing on the side of a road during one of her walks. Unfortunately, however, I've been physically unable to properly care for my once-lovely lawn in more than ten years, so Mother Nature has gradually replaced it with free plants she deems more suited to the area. She must be right, for the multitudes of noxious weeds grow with abandon, without any loving care from me. (Indeed, the plant I submitted may be among the crowds!)

All of the plants we call "weeds" are also wild flowers. What determines if a plant is a "weed" is if it is a plant you do not want growing where you do not want it growing it is a "weed". "Weeds" are simply unloved plants. That second picture does not look like nightshade to me. kimmq is kimmsr

I admit I had no idea what the name of that weed is. In my experience tassel flower is something with a fuller roundish bloom. Much more showy. On my property here in central Florida this is a plant with a very minimal “bloom”and a VERY invasive nature due to the numerous seeds, all of which seem to germinate. And that is not a seasonal thing, but year around germination and growth. So it is my recommendation to the OP, being in Florida also, to pull and destroy.