Don't think I've posted these before. From (as near as I can tell) the Caballero Formation, lower Mississippian. North of Lake Valley, New Mexico.
My best guesses are either Cupularostrum or Eumetria. Alas, I'm sometimes lucky if I get the right phylum.
Also embarrassed myself with this on this particular trip:
I breathlessly identified this as a really spectacular algal mound. Well, no; I had navigated up the wrong canyon, and in this geologically complex area, I wasn't even looking at sedimentary rock. This is spectacularly flow-banded rhyolite. If I can't tell a rhyolite from an algal mound, maybe I should just pack it in now ...