I know there is some poisonous Blackberry's - Called Snake berrys .
Many of the fruits of the solanacae family (which contains potatoes, tomatoes and eggplants) are poisonous. In fact, potatoes themselves can be poisonous if they have been exposed to light too long (developing green patches), and eggplants contain alkaloids which should be salted out beforehand.
Into this family come the nightshade berries, some of which are edible in small quantities only (as in some of the Australian species the solanum nigrum) but others of which, like the Deadly Nightshade, are as dangerous as their name suggests.
However, the alkaloids in the solanacae family can also be used as medicine, and science is looking for more ways to make use of these plants.
