That's a well-done grass texture. Have you tried a slight hue shift on the highlights or shadows?
The flowers are nice but don't look great sparsely scattered (I know this is just a tiling test mockup but I have to crit what I see), I'd try making patches of them, create a small and large as well as colors variations of each flower for making patches. They also seem a little over saturated compared to the grass; stand out too much. You might even create variations of your grass tiles that has little flowers in them for special use, such as patches of plants.
As for the overall tiling issue of looking linear/linking together well, you've actually done really well. Warcraft II uses this tile system, it's a 16-tile system, I've studied it in depth and have created my own entire sets before. It can be a lot of fun but also frustrating. Breaking up the inherent linear look of the tiles depends much on how you lay them out.
You have a tiling error bottom left, in the bit of grass that pokes out into the dirt from the left side.