Learn more about seeds by growing your own. Buy a packet of seeds at the store, or save the seed from an avocado or some poppy seeds. Put some dirt loosely into a small pot or cup, and poke the seed down into the dirt about half an inch down. Cover the dirt, and water the seed regularly until you see green sprouts popping up out of the dirt.
If you want, you can dig up your seed now and see what it looks like. What has happened? Where did the green part come from?