Flagstones of Trokair is a rare Legendary Land card from Ultimate Masters (UMA), collector number 243. Current market price: $3.69 (foil $11.13), TCGplayer market prices via Scryfall.
{T}: Add {W}. When Flagstones of Trokair is put into a graveyard from the battlefield, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle.