Years ago I got a seed packet of German Chamomile (Matricaria chamomilla) which I planted because my wife thought it'd be neat to have some for herbal tea. Since then it's nativized itself in section of the yard and so every spring I have a field of chamomile in which our ducks nest and plenty of critters hide. Even though it's kind of a pest, the flowers and sweet smell are kind of nice. There are worse weeds.