In a medium Dutch oven, melt butter over medium heat. Add celery, carrots, onion, garlic, and thyme; cook over medium heat, stirring occasionally, until vegetables are crisp-tender, about 10 minutes. Sprinkle flour over vegetables and cook, stirring, until evenly coated and lightly browned, about 3 minutes.
Add rice and gradually stir in broth, salt, pepper, and poultry seasoning. Bring to a boil; reduce heat to low and simmer, stirring occasionally, until vegetables are tender, about 30 minutes.
Add turkey; cook, stirring occasionally, until rice is tender, 10 to 15 minutes. Serve warm. Garnish with pepper and thyme, if desired.
Recipe by Louisiana Cookin' at https://louisianacookin.com/creamy-turkey-and-wild-rice-soup/