It took me awhile to figure out, but I realized why your cave looks like it's floating above the grass. It's because there are no blades of grass covering the low parts of the stones. Also, the top grass should look different from the bottom grass. I'm not sure how, but right now it looks like there's a hole in the top and you're looking through onto the grass below or something like that. The character looks out of place also. I like the rocks a lot, although you might want to make the shadows more defined and use a little blue in the hue to make it more realistic.