Feverfew (Tanacetum parthenium) reseeds in my garden every year, but only enough for me to be excited to see where it will come up every spring. My plants are kind of floppy when they bloom, but the daisies fill in beautifully around daylilies and basil and whatever else they're growing with.
The plants smell like Chrysanthemum, which I happen to like, especially since deer don't seem to. Feverfew is sometimes taken powdered or in teas or tinctures for migraine headache. I haven't heard any personal reports about this -- have you ever tried it?