Season burgers on both sides with 2 tablespoons of seasoning. Grill, turning once, until desired donesness or until the internal temperature reaches 160°F about 12 to 15 minutes.
Heat oil in a large skillet; add mushrooms and 2 teaspoons seasoning. Cook until mushrooms are tender, about 5 minutes.
Serve on hamburger buns, topping each burger with an equal amount of mushrooms.