I noticed these on my way to work, and went back this evening to get a picture. They're by the train tracks next to Fort Washington park, on the dry rough ground that had a big stand of evening primrose last August.
The size, varied colors, ruffles, and the fact that it's not in Peterson's suggests a garden escape; is there a reference book that everyone likes for common garden plants? Can anyone tell me what they are?
Notably, the stems seem to grow at an angle - the plants that have two flower spikes grow them in a v-shape.