This is a complete cobblestone tileset featuring all possible tile combinations with several alternatives. It has two sizes, 128x128 and 64x64. 32x32 can be generated from 64x64 as the cobbles cannot be larger than that version. There are two alternative grass textures. It is also possible to use it with transparent background.

This tileset uses the template from:
http://opengameart.org/content/complete-tileset-template

Cobblestone texture: 
http://opengameart.org/content/wall-grass-rock-stone-wood-and-dirt-480 

Grass texture 1:
http://opengameart.org/content/grass-with-moss

Grass texture 2:
http://opengameart.org/content/grass-001

 EDIT: changed preview so that it will not scale.