A tree V1 with ground, grass & stones. You can check out my profile for more versions. This is made in blender and rendered in cycles. The whole scene is quite low poly so after baking and a few optimizations you can also use them in your games. (You might only need to make the tree low poly). The whole scene uses just procedural textures, so you can bake it to whatever resolution that you want.

The plugin was used for the tree (blender sapling addon).This 3d model is UV unwrapped except for the tree.

Vertex / Poly count -->
Tree -- verts - 6950, faces - 3026
Ground -- verts - 289, faces - 256

You can check out my profile for more versions and more 3d models.