9. Elderberries
These berries are delicious but are only safe to consume when fully ripe or completely cooked. However, their seeds, leaves and stems contain traces of cyanide-inducing glycoside. Eating a large quantity of these cyanide-inducing glycosides can cause a toxic buildup of cyanide in the body and make you very ill. Eating unripe or uncooked berries can lead to severe diarrhoea and seizures.