There are a lot of wild berries growing where I grew up, and I was taught not to eat anything unless it fit certain criteria. Basically they always had to look like raspberries or blackberry type berries, the kind that looked like a cluster of tiny berries. There were also blueberries growing sometimes but those were rarer. Mostly it was wild blackberries and raspberries. All the others, i was told, were poisonous.

Now I never really considered what that poison would do to you, or if it was really a poison at all. Still, I never ate any to find out.

It turns out that most so-called 'poison berries' aren't really poisonous, they are just high in certain sugars which are undigestable to humans. As a result, the sugars ferment and expand in your intestines, giving you horrible cramps, flatulence, and explosive diarrhea. Of course, there do exist actual toxins in certain berries, like mistletoe. Many of them are fatal, including mistletoe. They can include respiratory toxins, nervous toxins, and cardiac toxins, or any combination of different kinds of the three. So don't eat strange berries!