This is a paid asset, but now you can download Stylized Grass PBR Materials Vol 01 for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
Stylized Grass PBR Materials Vol 01 v1.0
This pack contains a high quality stylized grass PBR substance. It can be randomized at the touch of a button offering multiple configuration elements.
There is also a PBR tesselation shader included so that what you see is exactly what you get.
Grass base color
Grass blade color
Grass blade amount
Prerendered Texture Resolution : 2048 x 2048
Number of Materials: 9
Texture format: PNG