Here is a winner!
"This wonderful plant loves poor, alkaline soil… the stonier , the better. It is drought resistant, very hardy, self-seeds but isn’t invasive, loves full sun and the summer heat, and flowers from the end of May until the first frosts!" From Words and Herbs.
Some call it "Centranthus ruber," some "Jupiter's Beard," I call it Red Valerian. Here it is in my garden this morning behind SUNNY INTERVALS;
...and here it is by itself;
The blue grey foliage and the tiny pink/red flowers go with anything. The flowers attract hummingbird moths and have no scent. Mine is about 30" across and tall and has been blooming since before daylily season. It does self seed but is not invasive as far as I can tell. Hardy zones 4 - 9.
Finally, here is a close-up of its bloom borrowed from the web;
