Commonly known as the Slipper Plant or Candelilla, it is native to the Sonoran Desert of Baja California and Sonora, Mexico. The crested form is highly prized and sometimes occurs naturally in the wild.
Actually, candelilla (meaning "little candle") is used for at least two plants in the spurge or euphorbia family (Euphorbiaceae). The other plant is Euphorbia antisyphilitica of the Chihuahuan Desert.
Enjoy your plants!