I used this video to learn how to use plant colors to dye eggs and imprint leaf shapes on the egg.
Helpful hint: make the hosiery as tight as you can to hold the leaves on and keep the dye from going under it.
Onion skins work very well; I also used dried elderberry and hibiscus flower. The other recipe I used was: 1 tablespoon of dried herb, 1 teaspoon of vinegar, and 1 pint of boiling water. Then I let the eggs soak at least 90 minutes.