Tanacetum vulgare (Compositeae) - Also called "bitter buttons", tansy was imported from Europe, where it was formerly used in cooking and folk medicine. Modern herbals discourage its use because it contains thujone, which can be fatal. Two of my books list it as highly toxic, never to be ingested, while others list it as a culinary herb. Go figure. It is nicely aromatic, and it is also listed as a useful deterrent to ants, who don't like the smell. Blooms late summer. (Photographed in WI)