Rhubarb
Rhubarb pie might be your favorite dessert in the world, but there’s only a small amount of rhubarb that can be used. Ingesting large amounts of this plant’s leaves can kill you. It’ll cause nausea, difficulty breathing, and kidney stones. This is due to the deadly oxalic acid, which will eventually cause kidney failure. Luckily, you’ll need to consume 12 pounds of rhubarb to get sick, which is very unlikely to happen. You can safely put the rhubarb leaves in your compost, though, because oxalic acid isn’t absorbed by the leaves (Taste Of Home).