Common corn-cockle (corncockle)
Agrostemma githago

It grows with a stem to 100 cm long with lanceolate leaves. The flowers are up to 5 cm in diameter, usually single at the ends of the stem. The sepals have 5 narrow teeth much longer than the petals. It has 10 stamens. It has slender pink flowers. It is a stiffly erect plant up to 1 metre (3 feet 3 inches) tall and covered with fine hairs. Its few branches are each tipped with a single deep pink to purple flower. The flowers are scentless, are 25–50 millimetres (0.98–1.97 inches) across and are produced in the summer months – May to September in the northern hemisphere, November to March in the southern hemisphere.
Each petal bears two or three discontinuous black lines. The five narrow pointed sepals exceed the petals and are joined at the base to form a rigid tube with 10 ribs. Leaves are pale green, opposite, narrowly lanceolate, held nearly erect against stem and are 45–145 mm (1.8–5.7 in) long. Seeds are produced in a many-seeded capsule. It can be found in fields, roadsides, railway lines, waste places, and other disturbed areas.