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

I was overwhelmed by the response to my first post, within 12 hours!  It
was reassuring to find out that it just isn't me that has problems with
teas.  So far it can vary quite a bit.  There is almost universal
agreement that chamomile and mint work.  From there it varies.  One
response noted that the mold in some teas was the culprit, another did
have problems with caffeine.  Some herbs are grown adjacent to wheat
fields, one person has a sensitivity to pesticides and uses organic
herbal teas.  One reminded us that "natural flavors" in Celestial
Seasonings may contain wheat traces, some from the supplier of the
flavors.  And of course, avoid those with barley.  Constant Comment was
OK with one.  One said that Lipton was GF, but I found that the Lipton
regular and decaf gave me a problem.
Will keep you posted to new findings.
B Hill in chilly MT, where a mug of hot tea is always welcome!