They are decorative onions, 'curious and beautiful' says Beth Chatto, whose descriptions of plants and flowers are enchanting and very accurate (I love her books). This allium has little papery cases which split to reveal the thimble like flowers, which, as they are pollinated, turn upwards again to make lovely seed heads. Unlike some alliums whose foliage flops on the ground, their leaves remain attractive - quite spiky, and staying upright, at least until hidden by the surrounding geraniums.
A lovely plant, easy and different. If it does have a common name, I don't know it. (Have just looked it up - Sicilian honey garlic? OK, but I like the way nectaroscordum siculum bulgaricum trips off the tongue.)
next posting - latin names and showing off....