A couple of people have mentioned John Barleycorn, but I don't think they've said it loudly enough. This is a song that seems to me uniquely English. There's nothing like it that I can think of in the American folk idiom, though we've absorbed lots of other English folksong types. We've got a Barbara Allen and a Gypsy Davy -- we even have the odd hunting song or two. But nary a John Barleycorn in the bunch.

Plus it's not *just* a folk SONG, it also represents some deeply English folkLORE as well.

And while we're on that subject, how about a May song?