If you are dealing with an organic, well respected herb/spice company they are probably dealing just with that product and therefore no gluten is involved. Now generic - I have no idea. Of course you could just email them - for a great selection though got to Penzey's . They are a great company with lots of varieties.
Not sure that this is going to help you but first of all take a good snack with you so that if you have to sit at the table, you can pick at the food only. Turkey without gravy should be ok, so should mashed potatoes unless they come from a packet (which I have idea if they are gluten-free). Some turkeys can be infused with 'stock/moisturizers' or something but not all of them. How does she make the bean salad? could you make that using gluten-free ingredients?
Of course your husband (and I love that he is supportive - that is so helpful) should tell the family that anything with ingredients that contain flour are not acceptable for you and make you very ill. Being able to be social and with family is important, and the meal is only part of the gathering, so try to be a little more positive and go for the people, and take a few dishes that you make to share.
plain potato chips are on the top of my pitstop snack list. Take some chex too. For the conference take the chex out of the package to make them smaller and put in your suitcase! I use them for early morning snacks or when dinner was lettuce leaves. gluten-free rolls are ok too - grab some butter and preserves from the breakfast table area.
A tip for the conference - find others on gluten free diets and vegetarian diets and sit with them - otherwise the rest of the table gets served while the server wanders off to find your gluten free option. Sometimes this takes a while, so having someone else there too makes you less conspicuous.