Starting with the environment. Just a simple ground plane that I subdivided and then proportional edited to get some good hilly parts where I wanted them:
I went over to @jlampel ‘s wonderfully short, but effective grass tutorial to fill out the ground. This is my mesh grass particle system, I weight painted out the area that I wouldn’t need for the scene:

The procedural portion of the grass particle system, and a sample render of the combined systems:

