Place chicken, onion, celery, 1 tsp. salt, 1/2 tsp. pepper, and curry powder in large pot. Cover with water. Bring to a boil; reduce to a simmer. Cook until chicken is cooked through; about 45 minutes to an hour. (I like to do this step in the crock pot on low in the morning before I go to work; then the chicken is done when I get home.).
Remove chicken from chicken stock; reserve enough chicken stock to replace water needed to make wild rice. Remove chicken from the bone and tear into bite-sized pieces; discard bones, gristle and skin.
Prepare wild rice according to package directions, replacing water with broth from chicken preparation. Preheat oven to 350 degrees.
When rice has cooked, add cream of mushroom soup and sour cream; mix well. Add mushrooms, 1 tsp. salt, and 1/2 tsp. pepper; mix well. Add chicken; mix well.
Place in casserole dish; place in preheated oven. Bake for 30-35 minutes, until casserole has heated through and top is golden brown.