Power berries, in short, will increase your stamina, depending on how many you find. At the beginning, your farmer will have none, but power berries can be found in various places in Mineral Town.
||How to Get
||Plow your field with your hoe until you find one (may take a while, there is no trick to this one).
||Plow your field again using your hoe to find another Power Berry.
||The morning you wake up to an earthquake, head on over to the Goddess’s Pond. Chop the tree stumps around her pond and one will have a hole underneath it. Drop down into the hole and you will be rewarded with a Power Berry.
||Catch a fish in the fishing pond and throw the fish back in.
||Go to the back hill and use your ax to chop up the tree stumps.
||Once you have achieved the Golden Hammer, smash the Chicken Statue with it at the crossroads.
||Sometime in the Fall an opportunity will arise where you can trade a Chicken for a Power Berry with the Peddler.
||At the Harvest Festival, bring along a Full Moon Plant or a Large Fish.
||Go to the Egg Festival and you can win a Power Berry.
||During the Winter, go up to the Summit and plant a seed of Snowflower.