Your latest edit looks ideal as far as unifying the dirt and the grass, though I would say the grass itself has a bit too high contrast and is fighting with the characters.
One thing to keep in mind is that, although tiles are in the play area in an RPG style game, tiles are still background elements. As Ryumaru pointed out, a flat color can work great on them sometimes due to the very fact that they are still *background* and thusly unimportant to detail, despite being in the play area still. It can look cleaner and more professional to keep the busyness down in the environment. After all, you're going for overall unity, not specific detail, in a screenshot. A good selection of colors and dramatic amounts of light and shadows can do more amazing stuff for your world than an amazing amount of detail (which pixels at this resolution are simply not built for in the first place).
