LINE baking sheet with waxed paper.
MICROWAVE morsels and peanut butter in large, uncovered, microwave-safe bowl on MEDIUM-HIGH (70%) power for 1 minute; STIR. Morsels may retain some of their original shape. If necessary, microwave at additional 10 to 15-second intervals, stirring just until morsels are melted. Cool for 1 minute. Stir in marshmallows until coated; stir in Goobers.
DROP by heaping tablespoon onto prepared baking sheet. Refrigerate until firm. Sprinkle with powdered sugar before serving.