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

Here are the responses I received.  I ran out and bought some of the
Early California black olives for a gf pizza and they were great!

Mario Olives available at Walmart and Sams Clubs are GF.  I confirmed
them with the manufacturer last Nov or Dec.  I don't have the phone
number handy right now, but can get it if you wish.  I think I have also
seen them on the shelf at Eagles and Krogers grocery stores.

In the TCCSSG shopping guide, they report 3 confirmed manufacturers:

Med-Foods (10-1999):
   Romulo Arbequina Olives
   Mas Portell Black Olives Pate

Santa Barbara Olive Co., Inc. (7-1998):
   All

Zorba (8-1998):
   Calamata
   Greek Black
   Spanish Green

I use Pelopponese (sp.?), which are generally packed in brine and have
no mystery ingredients listed. I have not checked with the mfr, since
the labeling is clear and the olives have never troubled me.

>From the CSA/USA, Inc. national organization for Celiac Disease, the
following S&W olives are GF. Extra Large Black (pitted), Jumbo Black
(pitted), Manzanilla Green (stuffed), Queen Green (plain), Queen Green
(stuffed) and Super Colossal Black with Pits.

Last year I spoke with Early California and was told that all their
olive products are gluten free.  The labels have not changed since then
but I have not reconfirmed their status.  I have been using them with no
problem.

So there you go!

Joanna