Brad, I brushed green latex house paint on the foam base. While it was wet, I covered it with sawdust from under my table saw. When the paint dried, I shook off the excess sawdust, then spray painted the base with a grass green color of Krylon. The latex paint seals the foam so it isn't dissolved by the solvents in the spray paint. Later, I randomly sprayed some other shades of green and brown on it so it didn't look too perfect. Finally, I sprayed some Elmer's spray glue on some spots, and shook on some model railroad "dense cover" grass, and some gravel (cat litter).
Sam