the ANSWER is: Nigella damascena
Pretty annual nigella (love-in-a-mist) is a fabulous plant for any garden, lending itself to cottage garden schems or more modern plantings, thanks to its unusual, sculptural good looks. It will readily self-sow if conditions are right: full sun and a light, well-drained soil. They're easy to start from seed in spring - just rake the soil to a fine crumbly texture and sow thinly in drills 30cm (12in) apart so they have plenty of space and light to grow.
H50cm (19in) S30cm (12in)