A close relative of common chives (Allium schoenoprasum), Allium tuberosum has garlic rather than onion flavored stems and leaves. Flowers are white and star-shaped, held in loose umbrella-shaped umbels, while leaves are long, flat and grassy. 

Bees love these nectar-rich flowers, which will self seed. Alternatively, divide large clumps in autumn or spring and replant. They will tolerate some shade.