I had no clue what this little guy was but using Peterson's "Beetles" and then BugGuide I think it is (just has to be) Ptinus fur. I assumed the little flecks of white were plant debris (which I didn't try to brush off because of the delicate nature of the beetle.) Turns out they are part of the beetle. Cool.

I was cleaning prairie seed (that had set for a couple of months) and all sorts of tiny insects, still alive, were found.