Source: https://ohioeggs.com/recipes/textured-easter-eggs/

Textured Easter Eggs
Use colored rice to create unique, Robin’s egg patterns on Easter eggs!
Ingredients
Hard-boiled eggs (white, brown or a combo of both)
Directions
- Step 1: Place about 1/8 - 1/4 cup of rice in the bags.
- Step 2: Drop 10-15 drops of food coloring in bags of rice.
- Step 3: Add in a little vinegar but do not let the rice get too watery.
- Step 4: Shake the bag gently to make sure the colored rice is evenly distributed around the egg.
- Step 5: Place eggs on a drying rack and let dry for 20-60 minutes.
Notes
It’s very important to not add too much vinegar to the rice mixture when using this technique. Excess vinegar will cause the rice to clump and stick to the eggshell. If you plan to eat your decorated eggs, make sure to use only food-safe decorating materials