Wait until one of your chickens lays an egg directly above the shipping box. Water the egg and it will turn into a block. Now pick up the "egg", and you will have infinite eggs, and lots of money!
Infinite eggs (Game Boy Colour Version)
Obtain a watering can and water an egg that is near the shipping box. It will turn into a fence. Pick up the fence and it will change into an egg. You will see though that the fence has remained, allowing you to pick it up again and again.
After you get the pick axe use it in the left room in the carven to clear all the block things on the top wall, you will find two lights use your pickaxe again in the vary middle and WITHOUT moving hit the wall 6 times.
That will make a hole walk through and you will be in the second pickaxe area (you will find 2 power berries in there).