O.K. Maybe what I have is Allium triquetrum. A few years ago a young man who worked for me gave me a few clumps of an allium from his grandmother's garden. No name. About 12 inches tall, grows in moderately heavy woodland shade under a carpet of sweet woodruff, Gallium odoratum. They flower simultaneously. The allium has clean white flowers and fresh green, grass-like foliage. Quite nice, but I've been negligent about trying to discover its name (after all, I figure the allium knows who it is.) A friend in England has been evicting masses of this from his garden. Shall I expect that some spring I will wake up to a sea of onions, so collecting sweet woodruff to make May wine will run the risk of instead producing an oddly flavored drink? Last winter was quite cold and snowy here in New Jersey. So if what I have is indeed Allium triquetrum then the hardiness is at least zone 6. Judy in New Jersey where summer has arrived, replacing the cool, gray, damp English version that we had until a week ago.