Here's a link for you, Kristi:
I have seen plates bent and used as a roof .on a wooden box type house .
Kristi, here are some more ideas. Some are different shapes! Have fun with it!
Cute! I've seen them with the license plate bent for the top roof over a wooden birdhouse. That would probably be the simplest approach.
Those birdhouses are really cute but I've found out recently there is a market for the old license plates. You might want to make your bird houses out of something else and display the plates or sell them.