In a large pot combine canned diced tomatoes, kidney beans, green beans, yellow beans, corn, chill seasoning, and chill flakes. Simmer on low.
In a large frying pan brown ground beef over med-high heat with some salt and pepper, Worcestershire sauce, and angostura bitters. When brown add to the pot of other ingredients and stir to combine.
In the empty frying pan add the mushrooms, onion, green bell pepper and garlic, and cook over med-high heat until onion is transparent and peppers and mushrooms are softened. Add these sauteed vegetables to the pot and stir to combine.
Simmer the chili for 2 hours on low, stirring occasionally.