Deadly Nightshade grows mostly on disturbed ground and woodland on calcareous soils. It's not particularly common but obviously one worth knowing. The whole plant is poisonous - particularly the leaves, and the solitary black berries are highly poisonous containing atropine (C17H23NO3) and scopolamine (C17H21NO4). They're said to taste sweet at first and therefore may be attractive to children. The pointed oval leaves are alternate on the stem. If this grows in your locality, make sure your kids know what it is!