We planted native grasses in the floodplain below our house last year, and here are some pics of how it looks now. I have to admit that I'm a bit fuzzy as to what are actually native grasses and what are annual weeds that have come up and are sheltering the grasses as they grow (Austin shows me, but I promptly forget). The grasses have such deep root systems that they spend most of their energy in the first couple years sending down their roots before they really get big and bushy. Austin mixed in some native wildflowers so we have some coreopsis, blanket flower and others down there now, too!