Everyone in Maycomb already knows that Tom Robinson is going to be transferred to the county jail, and a group of Atticus's friends congregate in his front yard to discuss the implications. Sheriff Heck Tate is a bit worried.
"I don't look for any trouble, but I can't guarantee there won't be any...
Link Deas adds that
"... it's that Old Sarum bunch I'm worried about...
"... know how they do when they get shinnied up..."
It is the same group from Old Sarum, mostly members of the Cunningham family, who show up at the jail with plans to lynch Tom. They expect the jail to be unguarded, since they have already taken precautions. When Atticus calmly warns them that the sheriff is "around somewhere," one of the men tells Atticus
"The hell he is... Heck's bunch's so deep in the woods they won't get out till mornin'."
"Indeed? Why so?"
"Called 'em off on a snipe hunt," was the succinct answer. "Didn't you think a'that, Mr. Finch?"
A snipe hunt, of course, is a type of practical joke initiated by one party that usually leads a second party on a "wild-goose chase." The Cunninghams had apparently falsely notified Tate of some form of non-existent emergency "deep in the woods," knowing that the sheriff would diligently pursue the call--and leaving the jail unguarded, except by Atticus.
She eats pie and got sick