Stick to cooked potatoes. These starchy things contain toxic compounds called glycoalkaloids that can mess up your digestive system.
Rhubarb leaves contain oxalic acid, which makes then toxic, so always discard them. Though you can eat the stalks raw, they will not taste great, so it's best to cook them.
These legumes contain a compound called linamarin, which turns into cyanide. Fortunately, cooking lima beans makes them safe to eat.
Eating just four or five of these raw can really hurt you. Red kidney beans contain lectins, which can cause severe gastrointestinal distress. These are destroyed during the cooking process.
While most mushrooms you will find in the supermarket are safe to eat raw, it's not advisable to eat wild mushrooms without cooking them.
Eating raw eggs can make you really sick. This is because they may be contaminated with salmonella bacteria. The only way to ensure they're safe to eat is by cooking them thoroughly.
Not every edible berry should be consumed raw. This is the case of elderberries, which should be boiled before consumption. These contain glycoside, which converts into cyanite and is therefore poisonous.