Peanut M&M's were introduced to the American public in 1954, 13 years after their chocolate counterparts made their debut. At the time, all peanut M&M's had a tan-colored shell; however, red, yellow, and green shells arrived in 1960, livening up the look of these classic nutty candies. They may have been the first variation of M&M's to be released, but they certainly weren't the last; over the years, the likes of almond, caramel, peanut butter, and pretzel M&M's have also appeared on grocery store shelves.