Rodney Smith Jr. was driving home in Huntsville, Alabama, when he pulled over to help an elderly stranger struggling to mow his lawn. That night he decided to mow free lawns for seniors, veterans and single moms. Then he asked kids to do the same: 50 free lawns each. More than 6,000 kids across the country have signed up. Those who finish all 50 get a new mower, trimmer and blower.