The S & S Seeds site has a bunch of cool seed mixes AND the extra cool thing is you can request a custom mix based on your particular criteria.
Their database for searching plants is also very granular and so useful.
Picture of bright orange California Poppies,Eschscholzia californica, in full flower and the interesting seeds heads that are exposed when the petals fall off. In the background and out of focus is a Convolvulus cneorum, a low ground cover with silver-grey foliage and white flowers.