Beans for Blind baking
Blind baking is when you cook a pie or pastry base before adding the filling. If you just gooi it in your oven un-beaned, the pastry shrinks away from the sides and air bubbles come up through the base. Nasty stuff.
Once upon a time, people used real dried beans to bake blind. But the dried beans got tired of being re-heated aimlessly. They wanted to fulfill their original bean destinies and become plants. So someone invented Baking beans and the bean population walked free.
Hey presto. Now you know.