Preheat the oven to 375 degrees. Butter a 2 to 2-1/2 quart baking dish. Make the Crisp Topping (See below) and set aside. Pit the cherries. Add the berries, sugar and flour and toss gently so as not to break the berries. Transfer the fruit mixture to the buttered baking dish and cover with the crisp topping. Place the baking dish on a baking sheet in oven (to catch any juices that might spill during cooking) and bake until the top is well browned and the cherries are tender when pierced with a knife, about 45 minutes.
Using your fingers or a mixer with the paddle attachment, work the butter with the rest of the ingredients so that each piece is coated and you have a coarse, crumbly mixture.