Big brains mined by a player in Survival, or destroyed by an explosion, drop a potato of knowledge with the same amount of experience stored in it (If the big brain didn't have any experience, a potato with 0 knowledge is dropped). The maximum possible amount stored in a single potato of knowledge is equal to 1000 experience points; if a big brain absorbs this much experience, a potato of knowledge with 1000 experience is dropped by it automatically, without breaking the block.
In the Minecraft:Creative inventory, three preset types are available: potatoes with 10, 50 and 100 experience.
Players can {{#vardefine: control | right click on mouse or left trigger on gamepad }}use the item to consume it. Potatoes of knowledge do not restore any hunger when consumed; instead, it gives the player the amount of experience that it stored. Because this item is not actually food, it doesn't count for the "Husbandry" advancement.
It also doesn't inflict the Poison effect, despite using the poisonous potato texture.