Final answer:
The boys stuffing their pockets with stones before the lottery in Shirley Jackson's story is an example of foreshadowing, a literary device that hints at future events.
Step-by-step explanation:
The description of the boys stuffing their pockets full of stones in Shirley Jackson's story is an example of foreshadowing, a literary device that gives an advance hint of what is to come later in the story. The use of foreshadowing in this case is particularly sinister, as it subtly suggests the horrific outcome of the town's traditional lottery without initially revealing its true nature. This method of storytelling serves to build suspense and engender a sense of unease in the reader.