Butter bottom and sides of 9-inch square pan, or spray with cooking spray. In large bowl, mix cereal and peanuts.
In 1-quart saucepan, heat corn syrup and sugar over medium heat, stirring constantly, just to boiling. Remove from heat; stir in peanut butter until smooth.
Pour over cereal mixture in bowl, stirring until evenly coated. Stir in candies. Press firmly in pan. Cool 1 hour. Cut into 6 rows by 4 rows. Store loosely covered.