Way back in the late 70s / early 80s, when I was living in New Jersey and part of a group that met Friday nights to play Dungeons & Dragons, there were group members who were particularly fond of something called "Dr. Brown's Cel-Ray Soda" and would order it at our post-game midnight diner runs. I never actually tasted it, but I gather it was made / flavored with celery, hence the name.

Do you have any notion about what Moxie was flavored with?