Purple cabbage leaves will give your eggs a purple/blue/lavender color. Don't be surprised if your eggs turn anywhere from a green color to purple or blue from the cabbage. Simply boil the leaves in some water until you get a purple tint.
Black coffee without any creamer will turn your egg a dark grey color.
Boil some blueberries for a deep purple color.
Beets and paprika both work well for red.
The skin of yellow onion and tumeric will help to give your eggs a yellow color.
If you are looking for a green tint you will want to boil the peels of a green onion. This will give a green/yellow look.
You are going to want to add some vinegar to each of these different mixtures so it sticks onto the egg.
Of course, the brown eggs will take much longer to dye as they are a darker shade than white eggs. If you are planning on using brown eggs, you will want to leave it sit for a while. If you want the eggs to be a very vibrant color, you may want to let them sit overnight.
Here are the eggs we dyed today!