Murmuring Bosk is a rare Land — Forest card from Commander Anthology Volume II (CM2), collector number 258. Current market price: $0.54, TCGplayer market prices via Scryfall.
({T}: Add {G}.) As this land enters, you may reveal a Treefolk card from your hand. If you don't, this land enters tapped. {T}: Add {W} or {B}. This land deals 1 damage to you.