"One April morning in Oklahoma, something terrible happened. A man parked a truck in front of a big building. Inside that truck was a bomb. The bomb exploded. People were hurt. And killed. But that was not the end of the story. Those who survived--and those who were forever changed--shared their stories and began to heal. Near the site of the bomb blast, an American elm began to heal as well. It grew new leaves. It produced seeds. It offered...