Just for everyone's information, the version of this map that's in-game right now has a lighter shade of grass. If there are no further comments on this image in a week's time, I'm going to re-upload this game with this map as you see it here.
I agree with LockeZ, I think this map is much nicer. The grass is a lot less artificial looking. As for the billboard, maybe move it above the pathway if that's possible? I don't know if that's an option but it would solve the problem of finding another sprite.