Hi Boo. There is always the obvious toy rabbit or chick, but that may be a bit boring. You could get them pretty much anything and put it in an egg shaped gift box, I think I've seen them around, or buy one that contains chocolate, eat the choccie yourself and use the box.
I'm not very up on the art of buying presents for children, but I have had to use my imagination when it comes to my parents as they like chocolate but you can still find last year's eggs around the place as my father hates wasting things, and scoffing chocolate and not savouring it is his idea of waste.