I'm not absolutely certain, and anyone who knows for sure can move the images. Scutellerids and pentatomids are close relatives. I followed a responder's suggestion on my other image and looked through the scutellerids. This genus in particular had a similar shape and markings.

I saw so many specimens that looked like these but varied in size, in the same place at the same time, that I thought they must be all one kind at different ages, including adults or near-adults. There was one adult-size stinkbug in the area, but it was plain brown with a bit of yellow in one spot at the middle of its back. Unless a very drab stinkbug has elaborately marked offspring, this was not a member of the previous generation of the same species as the present specimens.

I suspect that both kinds of bugs are in this flower patch now. It may be relevant that there are two kinds of egg clusters on the stems. Both consist of cylindrical white eggs (mainly white, that is, but some have gray bands across their middles), but the eggs are arranged differently. Some clusters are neat double vertical rows of eggs lined up along a stem. Others are "sloppy" bunches of eggs grouped around one point on a stem, roughly horizontal, the eggs on the outside of the cluster being attached to other eggs and not attached to the stem. I'd guess that two different species lay eggs in these patterns. One cluster of the latter kind hatched recently. The nymphs are small, dark, and roundish, mostly black but with some markings that my camera doesn't pick up well. I've put these on ID Request for comparison:

Then, very close by, there's this cluster, arranged in yet a third way: at the end of a stalk.

...and you may very well be right that these are indeed scutellerids. I am simply recommending that moving images into the guide be done in a conservative manner. If you aren't certain, and the other contributor prefaced their suggestion with "not sure", why make the leap to deciding they are indeed shield-backed bugs based on a superficial similarity to other images in the guide? (Not to be argumentative, but I think the few example images of pentatomids that I referenced in my last comment are just as close a match to your images in shape and color as the Orsilochides examples.) I leave it up to you to decide what's best, but my advice would be to place all these images at the level of Heteroptera until you get some more input from the experts.

In reference to the single adult bug that you found in the same area, it is absolutely possible for a drab adult to have elaborately marked offspring! (Just take a look through the images for Nezara viridula or genus Podisus.) On a long shot, I don't suppose the adult looked remotely like this individual? The reason I ask is because I have been noting with some interest that many of your nymph images show a fair bit of hairiness. I haven't done an exhaustive search, but this seems fairly different compared to many other nymph images of both pentatomids and scutellerids. The species which I referenced, Prionosoma podopioides, is I believe unique in having this characteristic and is also known from CA. Granted, the nymph images for this one currently in the guide do NOT look like your photos, but perhaps these are older individuals. Anyway, it seemed worth mentioning...

Since you asked, I've uploaded the stinkbug. For the sake of conservatism in placement, this time I ventured no further than Heteroptera.

This could be a case of a drab adult with fancy offspring. However, in the example you gave, each successive instar looks more like the adult. The bugs I observed of different sizes all had the fancy markings. If anything, the markings got fancier the bigger the bug was. The presence of an adult stinkbug in the area isn't conclusive. Several kinds of bugs (and flies and bees) use these flowers. There are egg masses laid out in three different shapes.

It would help if I knew how big an adult of this kind is.

If these specimens are expertly identified as scutellerids, the images won't accumulate such a long history of moves to clutter the pages as if I move them to Heteroptera and they end up coming back. They probably wouldn't stay in Heteroptera no matter what they are. If they turn out to be pentatomids, they can go directly to Pentatomidae instead of back out to Heteroptera and then to Pentatomidae or a genus or species page.

I asked at ID Request where someone else had a similar image. Maybe an expert will show up.