Common marsh-marigold (Caltha palustris)
Common, bright, early spring plant, growing in saturated soil and often found in roadside ditches. Native perennial, with bright yellow flowers 1-1 1/2" wide. Leaves are large, round, cleft at stem, with shallow teeth. Also known as Cowslip; toxic to livestock. The species name palustris means ?of a swamp or bog.?