You can thank Stu Roosa. He used to fight forest fires as a smokejumper (Yes, they jump into it) and later became a test pilot and was selected by NASA. He was the Command Module Pilot on Apollo 14. That position stayed in the command module circling the moon while the other two lucky bastards got to go land and walk on the moon. That position has the morbid responsibility of having to fly back to Earth alone in case of any tragedies. Anyway, because of his work with the forestry he took up the seeds as part of his personal kit, it wasn't a NASA program or experiment but something he did on his own.
If not for the Nixon budget cuts to the program he probably would have commanded an Apollo 20 mission and been the last man to walk on the moon for now.
I took this photo of his grave at Arlington in 2009.