The flat top approach and super straight edges to your rocks are making the entire composition feel very molded like plastic.
Your two highlight colors are extremely bright and in very high contrast with the other colors you are using (which are in themselves very saturated).
Your rockwork is very pointy and unnatural. The way you used the same general shape and flipped it back and forth has left the whole thing feeling fabricated as well. It doesn't seem natural and there is no feeling of cohesion between the stones. What is holding them together?
I've made a very quick edit to show you a grass style that might come close to the style of art you are using. You can use the same general idea. Flattened out on top sort of approach but suggest that it's still grass on top without it being a smooth plane. Perhaps the center is accustomed to being stepped on. Flatten out the grass. in the middle.
I also removed your too highlight colors and desaturated the whole thing quite a bit.
The stones still need attention in my opinion. It's a bit glaring the way they are stacked onto one another. Redefine the shapes. Consider the whole thing as a chunk of stone ripped out of somewhere perhaps. Stone doesn't break like that when it does break. Rather than long smooth edges, you likely would want more of a crumbly look.
