I think the mushroom trunk (where the little face is) is too undershaded considering how the cap has some many shades. Also, the cap is not just a flat thing on top of it, it's a half sphere-like object that casts shadow on the trunk. The trunk has too little contrast-- you can hardly tell that second shade is there. It also might be a little banded.
The tree stump looks decent (but I agree with E-man about the contrast), though on closer inspection, the outline on the roots looks a little jittery. Try cleaning that up.
Oh, just wondering, is there a particular reason why the mushroom is uneven? I mean, it's not a big deal, but nobody would bat an eye if it was symmetrical. Maybe the dots on the sides of the cap could be a little further to the sides to make the center look less crowded, too.
The tree stump looks decent (but I agree with E-man about the contrast), though on closer inspection, the outline on the roots looks a little jittery. Try cleaning that up.
Oh, just wondering, is there a particular reason why the mushroom is uneven? I mean, it's not a big deal, but nobody would bat an eye if it was symmetrical. Maybe the dots on the sides of the cap could be a little further to the sides to make the center look less crowded, too.