The "Autumn" theme for Moodle was developed by Patrick Malley of NewSchool Learning. It uses background images from "FallSeason" - a theme for WordPress developed by Sadish Bala. "FallSeason" is based on another open source WordPress design by NodeThirtyThree called Zenlike.
"Autumn" is a 3-column, fluid-width theme that was developed on the "Standard" theme for Moodle 1.7.1.
You are free to dissect, manipulate, and use this theme to your heart's content. I only ask that you continue to link back to NewSchool Learning, NodeThirtyThree, and Sadish Bala in some way. For your convenience, I have included a "Credits" page (credits.html) - linked to footer.html - to serve this purpose.