Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download HQ Photographic Textures Grass Pack Vol.2 Free.
HQ Photographic Textures Grass Pack Vol.2
This Pack contains of 140 Unique High Quality Grass Textures directly settled for using in Unity 5 (Alpha Blending adjusted, Perfect Background Color & Alpha Transparency).
From 4K(4096×4096), the Textures Files are compressed in 2K(2048p) in the Engine.
As the First Pack, they were all realized from Real Life Photos.
By using the Unity 5 Native Builds, Terrain Editors, Grass Shaders or any others Assets, the Textures are compatible and can be edited too in your own 2D/3D Softs.
For more informations, support:
Unity Forum Thread
Coupled to the Vol.1, you will have much more choices to combine and create your own Grass World.
Important: The Screenshots are made with others Assets, only the Grasses are included in the Pack.