Mostly need to know if anyone has any good tutorials on making land textures such as dirt, snow, grass. Also, any good skybox tutorials would be nice. The game I am working on happens to be MotoCrossMadness 2 if you are wondering.

well you can visit my site for textures, surrealtextures.com.
as for skybox textures download a program called terragen, it can be used to make skybox textures. here is a tut Clicky.

well our site is for those who don't have the time, programs or the skill to make good textures. our textures are also made well so they don't easily look repeated and they come with parallax, bump, and normal maps already made. along with that i've optimized the lower res textures to look quite good and sharp even though they're low res.
However you can do what the above poster said, np with making your own textures. and lol, we made the intro cheesey on purpose, i thought it was quite funny.