Keeping traditions alive

"I've been watching them for months. The girl salutes the memorial then puts something into a locked box. The man then comes about 2 hours later saluting the memorial like the girl and grabbing the contents of the box with his key. This has been going on for months now, and we still can't find out what they're doing.
I finally tell one of our younger undercover agents to talk to her at school. We don't talk to him for an entire month. When he comes to us again he just sits there and stares at the dashboard. Finally he tells us a story we'll never forget...."