Plants to use in a "rain garden" - rain water catchment basin

The drainage pipes from our new house open out into a collecting basin, or rain garden. It will be wet most of the winter, and completely dry during the summer here in coastal Northern California.  I need to cover it with plants. What ones would you suggest? Our coldest winter nights get to 18 deg F. It would be wonderful if they could serve other purposes as well.

Look for plants that suit ephemeral zones of rivers etc

Look at this site Ephemeral plantings California