I just posted a message in another thread about making how to make a rug, and while piddling around, I discovered it also makes some pretty wicked grass. Create a terrain. In editor, click new. Select a largish resolution (1024, say)for the terrain. Hit the spike key a few times. Flatten to taste. Don't anti-alias. For wilder-looking grass, use two terrains superimposed, with one taller than the other.