Blackberry Cobbler

This is SOOO yummy. My mom gave me this recipe and I don't think I've had better! And thanks Mom, these berrries came from her blackberry patch, they are perfect....thornless and the size of your thumb nuckle!

2 pie crust to fit 9 x 13

Mix enough berries for a 9 x 13 dish with:
2 2/3 cup sugar
1/2 cup tapioca
1 tablespoon vanilla

Dot with 2 tablespoons of butter. Fold over the dough around the edges and sprinkle with sugar. Bake at 400 degrees for 15 minutes, then at 375 degrees for 45 minutes or until it's bubbly about 2/3 the way into the middle.