All textures images are in .png format to keep original information and to have all the same file format.
Here are some textures for natural ground.
Here are some textures for ground made by human.
Here are some textures that can be tiled seamlessly. Some of them were hand made.
You'll need to have at least 3D Studio Max 2010 to use these materials libraries.
Here are some special materials for 3D Studio Max 2010.
... Work in progress ...
Documents, links, and software are provided "as is", without any
warranty, expressed or implied. I am in no way liable for any
damages, direct or indirect, caused by any of the provided documents,
links or software. You use them at your own risk.