Give back to your local school although you may not have children in that school. It’s as simple as cutting (I tear) the box tops off the boxes and putting them aside in a container. When you get enough saved up drop them off at the school, give them to a child you know, or mail them to the school.
I have no children in our local elementary school, so I either give them to the second grader up the street or take them into the school.
Many times, there are rewards for the classroom that collects the most box top points. The kids get excited they are being rewarded for their efforts and the ones that don’t get the reward – they work harder the next year.