Just taken dds entry into nursery - and it looks mighty fine, if i do say so myself!
I bought a large goose egg from the butchers, hard boiled it, rather than blew it to make it a bit more substantial. We then covered it in PVA glue and stuck yellow feathers all over, cut 'feet' and a beak out of orangey-yellow card, stuck those on, put on two googly eyes (you can buy those in big bags for less than £1 at Asda, Wilkos etc, then cut out two oval, wing shapes, stuck feather onto those and attached just at the top to make two flappy wings. We put an arganza bow with a flower in the middle right on the top of it's head, just to make it extra cute.
We covered a photocopy paper box in green card, with green fuzzy stuff on the 'ground' in the middle and made a picket fence and a gate out of brown corrugated card (although the box could just be painted), then got dd (she is only 3) to colour in big sheets of different coloured card and used a craft punch to make flowers from her handywork to decorate the chick's 'garden', with some little wooden ladybirds for extra effect! It looked great, really spring like, but was simple to do. An easter bunny, with white fur or even cotton wool, rather than feathers would also look good and could be surrounded with mini eggs.
One other entry I saw this morning that looked really good was an aquarium. It was a box painted on the outside in a bright colour then painted blue inside with green seaweed, etc painted on the back and up the sides. The 'fish' were eggs (3 in this one) turned sideways, painted in bright colours with cardboard fins and tails attached. They were then mounted onto cardboard tubes of different heights that were painted to blend in with the background so that it looked like they were swimming in the water, and there was gravel and sand on the bottom of the box.
On a similar theme, saw a picture in the local paper this weekend of a child who had one the competition at her school with a 'Nemo' egg. Again it just had cardboard fins and tail attached and was all with orange and white stripes with googly eyes and a mouth.
A few ideas there to keep you going!!!