<<Disclaimer: Verify this information before applying it to your situation.>>

Here is a list of replies I've received for g/f dry mustard:

Frontier Brand found in most health food stores or www.frontiercoop.com

Tones brand found in Sam's Club

McCormick's  found in grocery stores

Schillings Brand

Durkee's

Penzey's which is a large mail order spice catalog.  They also have a store
in Norwalk, Conn and two or three others out West I believe.  www.penzeys.com

Thanks everybody.  I found Frontier in the health food store near me.

Lisa Zafar
Orange County, NY