Prepare rice according to package directions, leaving out the seasoning packet. Set aside to cool.
Sauté celery and onions in butter until tender. Combine with croutons, prepared rice, water chestnuts, poultry seasoning, and almonds in a large bowl. Mix well.
Press into covered casserole dish. Bake, centered in 325° oven, until lightly browned, approximately 1 to 1 1/2 hours.