Giant Beaver is a common Creature — Beaver Mount card from Outlaws of Thunder Junction (OTJ), collector number 165. Current market price: $0.13 (foil $0.30), TCGplayer market prices via Scryfall.
Vigilance Whenever this creature attacks while saddled, put a +1/+1 counter on target creature that saddled it this turn. Saddle 3 (Tap any number of other creatures you control with total power 3 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)