Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9×13 inch baking dish.
Melt butter in a large skillet over medium heat. Mix together the zucchini, mushrooms, onion, tomatoes, salt and pepper, and add to the skillet. Cook and stir until the vegetables are soft.
Warm the tortillas 2 to 3 minutes, until soft, in the preheated oven. Fill the warmed tortillas with zucchini mixture and Monterey Jack cheese, reserving some of both for toppings. Roll the filled tortillas and place them seam side down in the baking dish. Cover with the remaining zucchini mixture. Top with remaining cheese.
Bake in the preheated oven 15 minutes, or until the cheese is bubbly.