Using a food processor, pulse bread until it crumbs. Lay on a baking sheet and toast 5 minutes or until lightly browned.
Raise oven temperature to 400 degrees F.
Heat a cooking spray coated frying pan over medium heat. Cook green onions and onions in pan for 5 minutes. Mix in mushrooms and cook 3 minutes or until mushrooms are tender and the majority of the liquid absorbs.
Stir in thyme and sauté 30 seconds. Take mixture off of heat. Add mushroom mixture, breadcrumbs, and bacon in a bowl.
Slice open trout and lay flat, like a book. Season with lemon juice, salt, and pepper. Place 1/4 cup of the mixture on the bottom portion of the trout and fold fish over. Lay fish on an aluminum foil covered baking sheet.
Bake 15 minutes or until fish easily flakes. Top with thyme sprigs and lemon wedges.