To easily gain coins, go to the barnyard after Ben tells you to use the metal detector to locate the Gopher's coins. Look for the yellow flowers on the right side of the farmer's house, then use the metal detector to find coins that are located there. At nighttime, enter and exit the party and use the metal detector on the side of the farmer's house to get more coins each time you do so.
Unlock the following keys by performing the corresponding tasks:
KEY - HOW TO UNLOCK Sharp Squiter (Barnyard) - Barnyard Key Nine Holes Golf - Old Mill Key Chasing Chicks vs. Otis - Walnut Woods Key All 18 Golf - Grizzly Gulch Key Defeat all Coyotes and Dag - Junkyard Key