Coreopsis lanceolata (Lanceleaf tickseed)

From CONPS: Perennial of 1-2' that blooms for weeks on end, creating an early summer display of golden yellow flowers. Butterflies are regular visitors, and songbirds feed on the ripe seeds in late summer. This durable plant grows in any well-drained soil, and prefers dry sandy soils. Can form extensive colonies. Deer resistant.