It's a contest between Sandmat and Rattlesnake Weed but I'm going with Rattlesnake Weed. It was interesting to see the various colors of it too.

I found these subtle differences in naming: Chamaesyce albomarginata va Euphorbia albomarginata

Rattlesnake Weed
https://cals.arizona.edu/yavapaiplants/ ... omarginata
https://www.americansouthwest.net/plant ... inata.html

https://www.inaturalist.org/posts/18984 ... ges-tucson

Small-Seed Sandmat https://swbiodiversity.org/seinet/taxa/ ... &clid=3056