Very nice-looking tile you have there
One thing you could try to make it look more interesting is to shift the hue a little. I gave the dark green a shift towards a cooler blue color and the light green towards yellow. Parts of objects tend to look cooler and less saturated the less light they receive.
If you want to avoid the mosaic effect kriss mentions you could make a second version of the tile with some variations, then break up the pattern here and there with your second tile.