Bridled Bighorn is a common Creature — Sheep Mount card from Outlaws of Thunder Junction (OTJ), collector number 7. Current market price: $0.15 (foil $0.23), TCGplayer market prices via Scryfall.
Vigilance Whenever this creature attacks while saddled, create a 1/1 white Sheep creature token. Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)