Comment by dustintrex

Not a bad survey of American mustard, but still missing several entire classes of mustard:

* French moutard a l'ancienne ("ancient" style), with mustard seeds left in. Maille's version is my go-to.

* Japanese karashi. Extremely spicy, so a little goes a long way, but a must for some Japanese dishes like oden.

* German mustards! Sweet Bavarian senf is obligatory for white sausage (weisswurst).