When Ted and I moved to a wooded part of Rhode Island, we never intended to become gumbo filé farmers. We didn't know that in our woods, among the pine and oak and maple, we would find several sassafras trees, or that sassafras -- often associated with the southern states -- actually is native to New England. And we didn't know that we could make filé powder from the dried, pulverized leaves of our very own sassafras trees. Filé (pronounced FEE-lay, and also called gumbo filé) lends an exotic, flowery, "root beer" flavor to gumbo, and when stirred in at the end of the cooking (as it always should be), it acts as a thickener. Though filé is most often associated with Cajun and Creole cuisine, it was the Choctaw Indians who first used it in their cooking, long before the Acadians arrived in Louisiana. I use it for gumbo, of course, and to thicken stews and lentil soups.