Garenbrig Squire is a common Creature — Human Soldier card from Throne of Eldraine (ELD), collector number 158. Current market price: $0.04 (foil $0.40), TCGplayer market prices via Scryfall.
Whenever you cast a creature spell that has an Adventure, this creature gets +1/+1 until end of turn. (It doesn't need to have gone on the adventure first.)