Attached Link: http://www.renderosity.com/mod/gallery/index.php?image_id=2043606

I've posted the image that has grass between stones. Originally that image was going to have a normal ground but this thread triggered me into using this technique instead. I used the 4th approach I mentioned above: the cobblestone ground is indeed a plane with stones extruded in zbrush and the grass ecosystem is set to populate only below a certain altitude (i.e, in the base of the plane).