Here's a great combination from native guru Darrel Morrison at NYBG's new native plant garden. I'm not sure what to think of the garden's hard-edged layout, but the plantings are fantastic. Too bad you probably need an engineered virgin soil, free of invasive seeds, to pull this off at scale — unless you have a big budget and an army of weeders.
Magenta Bush's poppy mallow (Callirhoe bushii) plays nicely with yellow black-eyed Susan (probably Rudbeckia hirta) , and white wild quinine (Parthenium integrifolium). Throw in a common milkweed (Asclepias syriaca) and prairie dropseed (sporabolis heterolopsis) for course and fine texture, and you have a very compelling arrangement.
A small slice of the meadow planting in the new native garden at the NYBG.