The Bear's Knowledge permanently increases the sell price of blackberries and salmonberries by 3x. The sell price of Artisan Goods made from blackberries or salmonberries is not affected.
To obtain the Bear's Knowledge, the player must find 秘密纸条 #23, then go to the Secret Woods with Maple Syrup in inventory. A cutscene ensues, in which a bear takes the maple syrup, and thanks the player by giving his special knowledge of berries.
Once obtained, it can be found in the wallet in the The Player's Menu on the Skills tab.