With a mouse, it's very hard to get the tapering effect of grass. Easiest way to do it is to use the grass brush which is included in photoshop then brush over it a little to make it look more realistic and less like a brush. You can also (if using regular photoshop instead of elements) adjust the direction and spread of the brush so that it looks even more like grass.
The crags in the stone/cliff/rock need to be deeper and more frequent. Right now, they look a little flat. Cliffs tend to have roots and plants and dirt sticking out at random areas. Small stones are also very common. A grainy photoshop brush will also help to add a bit of sandy texture to make it look more like it's covered in soil.
I really like the gnarled look of the tree. It's a wonderfully intriguing balance between sweet (the flowers) and darkly disturbing (the way the tree seems bent in on itself). I really like how your style looks. It's very expressive.