Here's one you can make with children (you do the cooking part, they do the filling part!)

your favorite 8-9" pie crust, baked (you can use the frozen ones)
1/2 cup water
1/3 cup cornstarch
3/4 to 1 cup fruit-sweetened blackberry jam or syrup
dash lite salt (or regular salt)
1/2 teaspoon cinnamon
4 cups fresh, rinsed and drained blackberries

instructions:

Stir water and cornstarch until smooth. In a saucepan, mix together syrup, cornstarch mixture, salt, and cinnamon. Heat on medium high, stirring constantly. Bring to a boil for about one minute, until congealed, smooth, and slightly darker. Fold in blackberries, and then spread evenly to fill the crust. Serve chilled or at room temperature.