Ed from over at Millard Fillmore’s Bathtub, along with “Kathryn the horticulturist” have correctly ID’d my mystery plant as Allowissadula holosericea, (Chisos Mountain false Indianmallow, Chisos Mtn. False Indian-mallow, Velvet-leaf Mallow.)
More here from Lady Bird.
And their reward? Another photo, my favorite actually. Even though it doesn’t show the open blossom, I like the composition.