My mom has been making this pie since I can remember, and now it is a staple in my kitchen. It uses quick cooking tapioca, and has a very fresh taste since you do not cook the blackberry mixture before baking. You can use fresh or frozen blackberries. I am always asked for the recipe when I take it to a pot-luck or gathering of friends. I love using Martha Stewart's Foolproof pie crust (Recipe #59026) for double-crust pies like this.