In the game, there are farmbucks, which are the regular form of money that you can use to buy a few things. Farmbucks can actually be earned in the game... Now, FarmCASH is different. Farmcash is purchased with real money and it can buy the cooler items, or the ones that are more helpful in the game. It can also buy you shortcuts in the game. Those phone card things are giftcards for Farmcash, so people can give them as gifts and others may redeem them. I've gotten and given a handful of them. However, Farmville is a stupid game and I wouldn't recommend playing it, or any other game by Zynga, because every path you take in the game leads you to having to buy stuff from Zynga. It's a waste of time and money.