Place the beef stew meat in the slow cooker and sprinkle with salt, pepper, and flour. Stir to coat the meat evenly.
Add the drained mushrooms, diced onion, sliced carrots, and cubed potatoes on top of the beef.
Sprinkle the dried thyme over the vegetables.
Pour the beef broth into the slow cooker, making sure it covers most of the ingredients.
Cover and cook on low for 8 hours until the beef is tender and the vegetables are soft.
Stir the stew gently before serving to distribute the ingredients and broth.