And among modern Wiccans (can't speak for the ancient Pagans, as I tweren't there) Lughnasadh is the sabbat celebrating the first harvest, particularly grain, and the death and ressurection of the grain god (and all that comes after that).

So, in that spirit, even though Lughnasadh is not mentioned in the song, I'd like to offer up John Barleycorn as a Lughnasadh ballad (this is from the DT mirror site).