Preheat grill on medium-high. Combine mushrooms, green onions, and roasted garlic in microwave-save bowl. Microwave on high 1-2 minutes or until mushrooms are tender. Set aside.
Cut tomato into thin slices to top burgers; set aside.
Sprinkle seasoned pepper over both sides of patties; place on grill. Close lid, grill 4-5 minutes on each side or until internal temperature reaches 155 degrees (for medium). During last 1-2 minutes of grill time, top each patty with 1/4 mushroom mixture and 1 cheese slice.
Place patties on bottom halves of rolls; top with pickles and tomato slices. Spread barbecue sauce and mayonnaise over top halves of rolls. Assemble and serve.