Very Nice! Would look great in a game!

In an actual tileset execution the parts where the rock is behind the grass would be one tile.. not two tiles overlapped..

Other than that I think it's excellent.. :)

Like everyone else said, the flowers definitely need more contrast, as they blend in too much with the rocks. Everything else looks good, though!

nice, I think you should give the flowers some outlines or a more contrasted color from the other tiles.

No, the dirt needs less contrast. The grass is fine. The rocks are perfect :D

The flowers need some contrast they blend in too much with the background. The grass and the rocks look good. The dirt is a little repetative. Pretty good for your first tile set. Good start make more.