At Chamberlins you can get a softgel by NewChapter called Supercritical Feverfew headache relief. It has 125 mg of feverfew per softgel. It's worked for me a few times but doesn't work all the time, although nothing really works for my headaches I hope that helps ya!
Chamberlins is a health store (ie. healthy organic foods, herbal remedy products). I'm not sure if there's many of them throughout the country though. You could probably find the product at a drugstore near you.