I’ve never been able to positively identify this. It’s either an aster or a close relative (my best guess would be a species of Senecio), but there’s nothing quite like it mentioned in any of my books on Kansas wildflowers. This is surprising, because it’s quite common around here. Normally the plants grow two or three feet tall, but if they are in a spot that periodically gets mown, they’ll form a mat an inch or two high, such as the plant pictured.