This is the tiny Verdin. It's only 3.5"- 4" (9-10 cm); the smallest bird I've seen other than hummingbirds. It's range barely reaches into the U.S. from Mexico, stretching from southern CA to Texas (along the Rio Grande Rvr). Their distinctive call (hear it) always let's me know when they're around.
Right now, I have to clean the house because Beth will be here in less than an hour to clean the house.
Edit: I have placed the original photo as an extra and after a couple of days of playing with the original replaced it with what you see above.