Blueberries are a useful food item that you can only find in food crates, similar to Black Raspberries.
Blueberries provide a substantial amount of calories and hydration when eaten.
The real value of blueberries is in the +10 health. Placed on your hotbar, you can consume a stack of blueberries quickly to restore your health.
Especially useful as eating blueberries is instant and does not have an associated animation.
This utility makes them invaluable during fights when you don’t have time to bandage or need to recover a small amount of health without putting away your weapon.
The drawback is the rarity of these berries. They can only be found in food crates, and cannot be grown as they do not yield seeds or clone plants.
As such, it is worth stockpiling them and pairing them with your PvP kit.