Yeah, I have wayyyy too much time on my hands right now! lol These are so easy I probably don't need to explain it, but I'll give you the abbreviated version anyway. When using eggs for cooking I've been cracking them close to the top and pouring them out instead of cracking midway through the egg like I normally would. I rinse the eggshell in warm water and let dry upside down. I used my hot glue gun to glue on plastic eye balls. If the kids are helping then let them use Elmers glue. Draw on facial features using a Sharpie. For these guys I just threw some soaked winter wheat inside and dampened slightly. You can add potting soil and seeds though, it just takes a little longer. Let it grow and voila...egg people!
I used the winter wheat because I had it on hand from Growing Fodder for Chicken Feed. I also use it to Grow Cat Grass for the indoor kitties. This is awesome because the egg heads were full grown in 4-5 days. The "hair" can be trimmed and it will keep growing for a few weeks. They don't need dirt, only water which is great if you have little hands or paws that might knock the eggs over. Unfortunately wheat only grows straight up, like grass. If you want something different just add your potting soil and try parsley, lettuce, lavender, chamomile etc. Anything really! You can break away the eggshell to transplant into the garden or a pot when it outgrows it's eggy home. (don't plant the whole shell unless you break off the piece with the glue and eyes first!)
Above all, don't forget to have some fun with it! It's not everyday you get to grow your own eggheads!