I like portulaca. We have a variety that's a weed here & doesn't produce flowers, but is sooooooooooooooo short.. it crawls around on the ground & never gets higher than say 1/2". There's some penstemons that might work as well.. they only get 2-3" tall and bloom nicely. I think I posted pix before. There's pineleaf penstemon & penstemon rupacola that are good ones for filler. Both of these are semi-evergreen in my area (mostly evergreen) and I know that if I accidentally squish either one they come back without squawking.
Pineleaf (red & yellow varieties) penstemon - this gets 3-6" tall and spreads.
Penstemon rupacola - this gets 2-3" tall
I also have an electric blue penstemon (Penstemon heterophyllus) that works out nicely for me as well. Not evergreen in my area though. Gets about 8-12" tall
