In a large saucepan, melt butter over medium heat. Add mushrooms and celery. Cook about 5 minutes or until vegetables are almost tender and most of the mushroom liquid has evaporated, stirring occasionally. Add chicken broth. Bring to boiling; reduce heat. Simmer, covered, for 5 minutes. Stir in cooked rice mixture, turkey, whipping cream and, if you like, dry sherry. Heat through. Makes 6 main-dish servings.