@croydon - That's actually a good thing to learn when you're a kid. If you're ever stuck in the wilderness and you aren't sure what is safe to eat, a burning sensation is one of the symptoms of poisoning to watch out for.
This is only for emergencies, but you basically try a berry or leaf by sticking it on your tongue for a little while without chewing or swallowing and then waiting to see if you notice burning or numbing. Then you try nibbling a tiny bit and wait for another hour to make sure nothing happens. Then you eat a little bit and wait overnight before you eat more.
Again, this is only in the most dire emergency situations, because it's still possible to die or become seriously ill from doing this, but it's the safest way of trying unfamiliar foods if you've got no other choice.