Okay, went trudging through my backyard in my bathrobe, much to my neighbors' delight I'm sure!
But got a couple good more close-up photos:
I do have several varieties of Rudbeckia fulgida in my yard, but most of them have wider leaves than this one has-- the leaves on this one are more narrow. I do have a Rudbeckia hirta that has more narrow leaves. Here is my R hirta, just about ready to bloom:
But the wildflower seed mix did contain the Ratibida pinnata.
Anyone have any thoughts on which it might be?