According to The Herb Companion,
Dip the hard-boiled eggs into white vinegar before beginning, and set aside. Then bring each dye ingredient (listed below) to a boil with 4 cups of water and 2 tablespoons of white vinegar; strain the dyes into small dipping bowls and allow to cool.
To dye eggs, dip them into the bowls for about five minutes, or longer for deeper colors. And be creative! Use two different dyes on one egg to create unique colors, or dye eggs half in one color and half in another. Below are the ingredients you need to get the best colors.
• Gold: Use 4 tablespoons of turmeric.
• Brown: Experiment with about 2 cups of strongly brewed coffee or tea for different shades of tan and brown.
• Purple: Use 4 cups of frozen blueberries.
• Light pink: Use a 12-oz. package of cranberries.
• Dark pink: Use 6 cups of chopped beets.
• Blue: Use 16 cups of chopped red cabbage (use 2 more quarts of water and 6 tablespoons more vinegar for this dye).
A similar article suggests using spinach to obtain the color green.
EDITORS NOTE: Some people with chemical sensitivities cannot tolerate vinegar.