If you're one that routinely purchases lots of premium animals and trees in FarmVille, your incentive to continue doing so has jumped up dramatically via the introduction of the new "Reward Cards" system in the game. Similar to cards you might have for real world stores in your purse or wallet, these Reward Cards are punch cards of sorts, that will keep track of your in-game shopping habits and will reward you accordingly.
In both the case of the Animal Reward Card and the Tree Reward Card
(please note that these are separate, so all purchases are tracked
separately), you'll need to purchase 10 animals or 10 trees at their
regular Farm Cash prices, and will receive a single stamp (or punch) on
your card until you've earned 10 in all. Once you've hit that point,
you'll receive a free animal or tree (depending on which card type you
actually completed), with a value of up to 26 Farm Cash. The way this is
displayed in the game, it's unclear whether we'll get to choose our
free prize, or if it will be generated for us, but we've reached out to
Zynga for clarification on the matter. Stay tuned for more!