why is it so hard to complete the easter build challenge? i can never get the egg, to even start decorating it

You have a dark chocolate egg in your nest, so you need berries on a low plate.  When the bunny is spotted, it will drop an egg onto your plant.

Taken from Tracey's wonderful guidelines on the forums:

BUILDING THE EASTER EGG

This year (2026) you have to get some of the parts in a specific order.  You must start with the Egg  (dropped by any Easter wildlife EXCEPT the Easter Bunny), and you must finish with the Main Design (dropped by the Easter bunny).  The other parts can be added in any order.  All are dropped by the Easter wildlife which you ATTRACT to your garden (NOT WHICH YOU SPOT IN OTHER GARDENS).
 
These are the parts and the items which drop them:
 
   The Egg (dropped by all Easter Wildlife except the Easter Bunny) MUST COLLECT FIRST!
   Marbling (dropped by Easter Chicks)
   A Pattern (dropped by Seahorses)
   Flowers (dropped by Chocolate Bunnies)
   Main Design (dropped by Easter Bunny) MUST COLLECT LAST!

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As Rachel states above, you need to put berries on a low platter to get your egg.  You WON'T get it from your Easter Bunnies.  Your left hand Easter Egg plant is now around a week old.  I would be tempted to dump it and focus on the other plant you have.  You'll have a lot more time on it to build your egg.

Good luck