Realistic looking Grass

[FrankThomas]

Does anyone have a source for realistic looking grass that I can populate quite densely but which isn't going to massively extend the render time ?  So far I'm just using a sort of greenish/yellow surface shader but it's not ideal.  The "Grass clump" object isn't really what I'm after

[Doofus]

Have you tried mixing up some tileable photographic grass textures with different repeat values to break up the tiling effect.

[FrankThomas]

Not yet - I haven't figured out how to do that bit yet 

I'll probably be spending most of the weekend fiddling around with stuff so we'll see what happens