Gifting to people is a good way to get them back. You might want to keep a list of you who gift to and who gifts back. Sometimes requesting specific gifts in your status can get a nice flood. Normally – If I get trees, i plant them. If i get animals i sell them for the extra money boost (Small as it may be). You should always try and gift the highest thing you can since they almost always give the best return (Unless someone requests one)

Gifts are also randomly received from doing achievements, and although (Like regular gifts) you do not receive Exp from planting/placing them, they can be sold. Sometimes its best to keep them for future Achievements.