Many mainstream candy bars (and popular candies) are gluten-free. While most GF candy bars are not produced in dedicated facilities, the manufacturers do follow regulated standards for cleaning the equipment between products. Below are a few of the popular candy bars (and candies)* that do not contain gluten:
M&Ms (plain and peanut)
Nestles Milk Chocolate
Reese’s Peanut Butter Cups
*For a complete candy list, see Clan Thompson Gluten-Free Food “SmartList 2008” (CANDY): http://www.clanthompson.com/.