What was in pauls pocket bedknobs and broomsticks?

In the Disney film "Bedknobs and Broomsticks," Paul, the young boy who lives with the three children, has a lucky charm in his pocket. It's a small, silver object, which he calls his "lucky charm."

He pulls it out and shows it to the children when they're feeling down or scared, and it seems to bring them a bit of luck.

While the film doesn't explicitly state what the charm is, the children refer to it as a "lucky charm" and it's depicted as a small, silver object.