Texture Research and Tutorials

Online Tutorials
Grass:
http://www.myinkblog.com/create-an-awesome-grass-texture-in-photoshop/

TreeBark:
This texture would require the use of photos and find away to make one which has seamless edges which makes the texture easy to tile.
Stone:
http://www.myinkblog.com/creating-a-realistic-stone-texture-using-photoshop/
Nice for the exposed rocks that will be doted around.

Brick
http://custommapmakers.net/index.php?option=com_kunena&func=view&catid=18&id=399&Itemid=54
http://photoshopcafe.com/tutorials/brick/brick.htm

A very good tutorial which can be applied to all different types of Bricks.

Water:
For water i've decided that you can create a descent looking water by using the settings provided in the 3ds program its self. Setting the color as blue and lowing the opacity should create this.