Allium sphaerocephalon L. syn. Allium sphearocephalum, also called "round headed garlic" (sphaero = sphere, cephalum = related to the head) is an easy to grow onion that produces very dramatic flowering heads in early summer. It is grown in many climatic regions in the United States including the Deep South. It is frost hardy, drought tolerant, best grown in full sun and well drained, fertile soil with extra lime. The species can be propagated vegetatively by bulbs and bulbils. A single bulb produces about 4 bulbils at the end of the growing season in early summer. The first two photos below were taken by Nhu Nguyen; the remaining photos were taken by David Pilling (the coin is about an inch in diameter). The last shows that the flowers do not open widely when the style and stamens appear.
Photo 1 shows a flower that was covered by foliage from nearby plants, and produced bulbils instead of a full flower. Photo 2 shows pollinated flowers forming seed pods. Photo 3 is of seed. Photo 4 is of a bulb accidentally uprooted whilst still growing, showing bulblet formation just below the surface (the stem is visible to the top left).
Photo below of the ripening seed pods by Travis Owen.