Once a day, you can send a gift to five of your friends. To do this, find a player in the list of your friends and tap the "Send" button under their icon. A player to whom you have already sent a gift will be marked with a green checkmark.
Friends can also send you gifts. In this case, you will see balloons on your farm. Tap on it to pick up the gift. As a gift, you may receive coins, Westbucks, a stamp, coupons, and useful items for participating in special events.