The east expansion costs 500 coins and does nothing at all, you cannot see anything happen.
Youd get a new vegetable upgrading to certain level, however, most new ones earns less per unit time. While it seems wise to plant old ones like lettuce or camomile, it would not help you in inviting new friends and getting new pages.
Otherwise, this game is perfect.
JohnPolchinsky about ピーターラビットガーデン, v5.4