Yellow Starthistle (Centaurea solstitialis)

Centaurea solstitialis is a tap-rooted annual forb in the Asteraceae (Sunflower) family.
They have yellow solitary flowers with stiff, 1-inch spines protruding from their involucre. Their basal leaves are deeply lobed, upper leaves are small and sharply pointed, and while leaves and stem are covered with cottony fiber