Heap Gate is a common Land — Gate card from The List (PLST), collector number CLB-354. Current market price: $0.35, TCGplayer market prices via Scryfall.
{T}: Add {C}. {1}, {T}: Add one mana of any color. {1}, {T}, Tap an untapped Gate you control: Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")