Ah, that one. The one which, when consumed by dairy cattle, makes milk and cheese taste garlicky! We have a lot of three-cornered garlic in Cornwall, Allium triquetrum, which some people use in cookery. The nicest one, very abundant in these parts, is Allium ursinum, which we call ramsons or just wild garlic. Adds a nice mild garlicky touch to any dish you like.