That night in bed I pulled out a booger and asked it myself. I knew I had to listen very hard to hear the answer. So I did. I didn't listen with my ears though. I closed my eyes and listened with my mind.
Boogers come from the booger fairy.
At night when you are sleeping this fairy flies into your window with booger dust. It is a green powder. She uses a special straw and blows it up your nose. It tickles a little, but not enough to wake you up. That is why you have the most boogers in the morning.