Summary
Apollo 14 launched on January 31, 1971. Five days later Alan Shepard and Edgar Mitchell walked on the Moon while Stuart Roosa, a former US Forest Service smoke jumper, orbited above in the command module. Packed in small containers in Roosa's personal kit were hundreds of tree seeds, part of a joint NASA/USFS project. Upon return to Earth, the seeds were germinated by the Forest Service. Known as the "Moon Trees", the resulting seedlings were planted throughout the United States and the world. NASA Space Science Data Coordinated Archive Lead Dave Williams has made it his pet project to find out what happened to the Moon Trees.
You can find out more about the Moon trees on the NASA website.