There's a Spinach Mushroom Strata at this site:
astray recipes: Spinach mushroom strata
This one doesn't have spinach but is a good one anyway:
CHEESE & EGG STRATA - serves 6-8
3 slices bread, cubed (about 2 cups)
1/2 lb grated sharp Cheddar (2 to 2 1/2 cups)
1/4 cup diced green pepper
1/4 cup diced celery
1/4 cup diced onion
1/4 cup sliced fresh mushrooms
3 eggs
2 cups milk
1 TBL prepared Dijon mustard
1/4 tsp salt
Cayenned pepper to taste
2 TBL butter
Preheat oven to 325°. Place alternate layers of bread & cheese in a well greased 13x9" baking dish, ending with a layer of cheese. Combine green pepper, celery, onion & mushrooms & sprinkle over bread & cheese mixture. In a small bowl, combine eggs, milk, mustard, salt & pepper. Pour egg mixture over bread, cheese & vegetable mixture. Dot top with butter. Bake 45-60 minutes. Let stand 5 minutes before serving.