Heat oil in a large skillet over medium heat. Saute the mushrooms, celery, and onions until softened.
Dampen the fresh bread cubes (not the stuffing mix), then squeeze out any excess water.
In a large bowl, combine the mushroom mixture, bread cubes, stuffing mix, eggs, and 1 can chicken broth. Season with sage, thyme, garlic powder, salt, and pepper, and mix well. The stuffing should have a rather paste-like consistency. Mix in additional chicken broth as necessary.
Loosely pack stuffing inside turkey cavity before roasting.