Autumn To May (in the DT)
Equinox
Falling Leaf
The Seasons
The Best Of Autumn (thread here)
Autumn Gold
Forever Autumn
Changin' Of the Seasons
My Lady Of Autumn
Lady Of The Seasons' Laughter

Songs that mention autumn:
Both Sides The Tweed
April, Come She will
Promises Broken And Kept
Puff, the Magic Dragon