Garlic came from Old English Garleac, a combination of Gar (an archaeic word for spear) and Leac (Leek, which referred to all alliums at the time)

Other onions used to be called leeks too
Ynneleac -> Onion
Crawleac -> Crowleek (Allium Vineale)
Ryscleac -> Rushleek (Chives)

Unfortunately, there's a bunch of -leacs that we don't know what they referred to