Preheat oven to 350°F. Boil lasagna noodles according to instructions. Drain the mushrooms and reserve the liquid. Mix together cubed turkey, onion salt, 1/2 cup mozzarella, 3/4 cup gravy, mayonnaise and mushrooms. Put the reserved mushroom liquid in with remaining gravy.
Once noodles are done rinse in cool water. Put the turkey mixture onto the lasagna noodles and roll up. Then mix the remaining gravy with the remaining ingredients of 1/2 cup mozzarella, 3/4 cup gravy (with juice from mushrooms) and pour gravy over top.
Let bake in oven 30-45 minutes when you see it is golden brown on top and bubbly.