my fave is a series of songs from one of the libana cd's. they all have gorgeous melodies and can be sung individually as rounds.

fly fly fly
the leaves are leaving the branch
cold is the wind
winter is coming

sing, oh, you falling rain
dance, oh, snow
flow you river, river, river,
blow, wind, blow

autumn time
red leaves fall
while the weeping sky
looks over all
demeter sadly walks the land
the dying grasses in her hand

and another especially for samhain:

ancient mother, i hear you calling
ancient mother, i sing your song
ancient mother, i join your laughter
ancient mother, i taste your tears