When I saw this beautiful caterpillar on my meadow rue one evening (5/29), I thought it would be pretty easy to identify since it had very distinctive markings and coloration.
And yes, it was easy, using Google lens. It's the Canadian owlet moth, Calyptra canadensis, which feeds almost exclusively on meadow rue!
Suddenly this association caused some sparking in my brain, and I searched for 'caterpillars' in my collection of digital photo albums. And yes, I found that I had photographed this same species on May 27 2021, and posted about it on June 9th (Sitting Quietly). I hadn't remembered the species name, nor the distinctive markings.