They're in the onion family, possibly wild onion or allium flower bulbs planted years ago. You can't cut them back without ruining them. That's the flower coming up.

This post was edited by susanzone5 on Mon, May 27, 13 at 20:50

allium sphaerocephalum - aka drumstick allium. They will seed about and spread so you might want to dig a spadeful out this autumn. Nice maroon and green flowerheads which assort well with most perennials.