Coins

Coins are the only currency in Pocket Frogs.

The in-game symbol for coins is three blank golden coins stacked on-top of each other. Other than the raised edges, there is no decoration of note on them.

Coins can not be used to buy stamps or potions.

Earning
Coins can be earned by:
 * Receiving coins for a Daily Gift (the amount varies)
 * Selling frogs (maturity and happiness determine the amount of coins gained. Rarity determines the max. value)
 * Selling scenery (the quality determines the amount of coins earned)
 * Finding pond presents (the higher level the player is, the more coins will be earned. If one declines a scenery/frog present, one will instead receive coins determined as 1/4th of the item's value, rounded down.)
 * Winning mini-games such as:
 * races (the rarity of the frog determines the prize amount)
 * puzzle (the rarity of the frog used has no effect)

Uses
Once earned, the player can use coins to:
 * Breed frogs (rarity affects the breeding fee)
 * Buy frogs from the FrogMart or clone already-discovered frogs from the Froggydex.
 * Buy scenery or habitat backgrounds from the Supply Shop
 * Buy new habitats (only purchasable if the player is a high enough level)
 * Play certain mini-games such as races or search (rarity affects the entry fee)

Trivia

 * When breeding two frogs, the player will earn an amount of XP equivalent to the amount of coins it costs to breed the two frogs. E.g. if it costs 37 coins to breed two frogs, you earn 37 XP every time you breed.

Pocket Frogs Coin Value Database - Android v3.X