Acorns are like the easiest thing to forage, though.

They are high in tannins, which your body is pretty good at processing in reasonable quantities (they’re in tea, coffee, and wine), but many acorns DO have unreasonable quantities of them and they can cause organ damage. Luckily, tannins are water soluble, so you just need to crack them open and soak them in water for a few days, then rinse and they’re safe to eat.