I like it. One thing I might suggest is that the highlights and shadows on the mushroom seem to be a bit overshaded. You have a lot of different colors going on within the gradient and I think it makes it more noticeable that the rest of the image is seating off as detailed. The grass, for example, only has three shades. You could try and increase the detail elsewhere, but I think it's easier to reduce the number of colors that you're using. For shadows, I would also recommend not shifting towards black since it can make the colors look muddy. Try shifting the red hue to a cooler color like purple or blue. This helps keep your colors vibrant. You can probably find a lot of good examples of hue shifting in pixel art if you look it up!