Tomatine is a toxin that is typically found in the leaves and stems of tomato plants. Large quantities are reported in green tomatoes, so be careful to remove and just consume the tomato itself.
Brazil nuts is considered one of the most radioactive foods. Fortunately though, if eaten in moderation the majority of this is not retained by your body.
Potatoes contain excessive amounts of solanine which could lead to poisoning if you are consuming green potatoes. So make sure your potatoes are fully ripe before consuming.
The green leaves of the Rhubarb are dangerous as they contain oxalic acid which can lead to formation of kidney stones if consumed.
The pits of cherries contain hydrogen cyanide which can cause breathing difficulties, vomiting and sometimes kidney failure.