All forest backgrounds in my db folder, locations\dungeons\forest.
I have divided backgrounds into three groups, normal, elven and dark. Besides, I've found a good deal of pics for forest ruins, so we either could make a separate tiles for them, or player randomly could find ruins during exploration.
Unless you agree to use pics of real forests, I doubt we can find any more backgrounds.
As for item hunting, I'd prefer to not concentrate on mobs only and create events for rare items like finding forest ruins with a chest guarded by several mobs or even mini-boss.
Enemies are basically random characters with battle sprite and portrait. As for mini-bosses and maybe even bosses, we could use usual mobs with higher stats and different names, at least for alpha.