The glorious Allium ‘Globemaster.’
Michelle and Laura B. nailed it, and Jennie had the correct genus.
A little taxonomic correction – it is NOT A. giganteum, as many catalogs and articles suggest, but rather a hybrid between A. macleanii and A. christophii; described by the breeder himself – Jan Bijl – in a 1990 issue of The Plantsman (vol. 12 pp 152-156). Unless I’ve totally messed up and this is ‘Gladiator,’ not ‘Globemaster.’ They’re quite similar.
Big blobs of floriffic fun, none the less. A bit pricey at $5 to $8 per bulb, though. I only have five in the ol’ home garden – that’s about as "en masse" as I can afford.