This is a picture I took of my mystery weed out by Pittman wash in Henderson NV earlier this year. From my experience this last year, I assume that the plant turns red later in the year and loses the bottom leaves. The plant typically seems to grow no more than half a foot tall but can grow a couple feet wide at or near the top. Edit: I wasn't able to get a background but here are more pictures
3$\begingroup$ The spindly nature of those stems makes it hard for the camera to find a focal point. Maybe try getting down low and have the camera focus on the basal leaves, and if the depth of field is good we'll be able to see the stems as well. If you are taking photos with a phone be sure to sit down (for steadiness) and tap the image where you want it to focus -- sometimes they need a little guidance! $\endgroup$– Bryan HansonAug 2, 2018 at 14:58
$\begingroup$ @BryanHanson Thanks, I'll take a better picture when I get a chance later today. $\endgroup$– tox123Aug 2, 2018 at 16:05
1$\begingroup$ If there’s a lot of that plant around, you might pick one of the stems, and bring it home and photograph it on a neutral surface. Might be easier to get focused there. $\endgroup$– Bryan HansonAug 2, 2018 at 16:06
$\begingroup$ @BryanHanson idk if these are better but I picked one and took some pictures. $\endgroup$– tox123Aug 9, 2018 at 15:57
1$\begingroup$ Those are helpful, thank you. Not a lot of plants generally w/o any leaves (ignoring the tiny basal leaves that are probably from when it sprouted). Someone will know this plant, I may have time later to dig through some field guides. $\endgroup$– Bryan HansonAug 9, 2018 at 16:27
Alright, after a lot of searching, I have a proposed ID: Eriogonum deflexum known commonly as skeleton weed or little desert trumpet. I feel pretty confident of the genus, less so on the species (there are several close candidates). The family is buckwheat or Polygonaceae.
This plant has basal leaves as yours does, has pretty much leaf-less stems and relatively infrequent flowers, which look quite a bit like your picture. Reading various descriptions it seems the plant is somewhat variable, it often looks like your pictures but sometimes has more flowers and sometimes the plant is more dense, rounded, shrubby and taller (it probably depends on the moisture and soil quality). It is a desert species, preferring scrubby areas and washes, widely distributed in Western US deserts.
CalPhotos has a picture which looks to be a good match (credit: Jean Pawek; also, CalPhotos has many other photos). This photo by Hank Jorgensen looks like a good match too and shows flowers which look similar to yours.
If you see the plant again, bring a picture on your phone and check the flowers carefully. Also the leaves should be hairy/wooly.
$\begingroup$ Yes, the leaves are frequently wooly. Thanks! $\endgroup$– tox123Aug 15, 2018 at 2:56
1$\begingroup$ Great! I've been semi-obsessing about this! Found it by browsing a field guide to San Diego county plants and fortunately it was there. $\endgroup$ Aug 15, 2018 at 4:53