More info from Walter: see http://www.walterreeves.com/gardening-q-and-a/black-nightshade-poisonous/ I had read before that some (or all?) of the closely related species of nightshade might be edible, or edible under some circumstances, i.e., if totally ripe, or cooked, etc. But I was under the impression for so long that they were poisonous, I thought best to suggest that. Maybe with some more research, it might be worth cautiously trying.

That is Solanum americanum, American Nightshade.

Nightshade. A tomato relative, but fruit generally poisonous.