It's been a great year for Black Nightshade (Solanum ptyscanthrum) here at Tropical Texana. So why, do you ask, would I keep a plant like deadly nightshade around?
To begin, it has very pretty berries and it grows naturally since it is a Texas native. Secondly, I have watched a mockingbird eat all the berries off a plant and not fall over dead. So somebody likes it for food.
HOWEVER, if you have it in a field with cows (that hopefully does not describe your garden! :-) or you have small children, do not let them eat it. The unripened, green berries are especially toxic and can cause a fever, stomach cramps and vomiting. It's not the same plant as the more famous version shown below. That species grows in Europe.