Carrion Grub is a common Creature — Insect card from Commander Masters (CMM), collector number 143. Current market price: $0.25 (foil $0.28), TCGplayer market prices via Scryfall.
This creature gets +X/+0, where X is the greatest power among creature cards in your graveyard. When this creature enters, mill four cards. (Put the top four cards of your library into your graveyard.)