Line a baking sheet with waxed paper. Bring the sugar and corn syrup to a boil in a saucepan over medium heat; stir in butter and peanut butter until thoroughly mixed, and remove from heat.
Place the corn flakes into a large bowl, and pour the peanut butter mixture over the cereal. Mix until the corn flakes are coated with the mixture. Drop by tablespoon onto the waxed paper; flatten slightly if desired. Allow to cool before serving.