One way to reuse them Easter eggs instead of having them collect dust. Grab some soil and seeds and let your child start their own garden. These eggs make for good seed starter containers(make sure the eggs have the little hole before planting, it is needed for draining water) and once the sprout is big enough can easily be taken out and placed in a garden or pot. I will updated as our seeds grow but this is a idea we have done before and know it works.
P.s. this idea works great with real egg shells too! and once the sprouts grow they can be planted as is in the egg shell.