Thanks for your help with identifying this plant. I was able to search back through my photos using your suggestions and I suppose it is this aster. For some reason last fall I had decided it was something else, but didn’t take recent pictures. This is from 2006 so I should know it well by now, but must have put up a mental block.
The past several years I have not stayed on top of the garden and this plant is running thoughout my irises and taking over, as I showed in the last post. Guess I’ll start pulling it out again!