It looks like it is a "magic" mushroom; it makes you see things that aren't there.

(Seriously though, ALWAYS consult the experts before foraging for edibles, especially mushrooms! When in doubt, only buy them from the supermarket.

Also, "The Adventures of Gobold and Dicebreaker" does not condone the use of hallucinagens under any circumstance.)

PSA disclaimer done, back to the Adventure once their "trip" wears off...