Reese's Pieces are small blobs of peanut butter surrounded by a crisp candy shell. They come coloured in yellow, brown and orange (like the Reese's logo).
You may remember this candy from one of the earliest examples of mainstream product placement in Hollywood movies. Reese's Pieces were used in E.T. The Extra-Terrestrial - they were spread along the ground as a lure. And what a delicious lure!