Who was one of the men on the jury in To Kill a Mockingbird by Harper Lee?
Most of the men on the jury are from "out in the woods," not Maycomb citizens with whom Scout or Jem are familiar. Atticus explains Maycomb citizens either don't care about the trial enough to be on the jury or are scared of getting involved in the whole trial, so they make up excuses to avoid being on the jury. As a result, when Scout watches the trial, she always just sees the jury as a sea of unknown faces.
Eventually, Scout and Jem learn from Atticus that one of the members of the jury is actually related to the Cunninghams. Specifically, he's a "double first cousin" of a Cunningham. If that sounds odd, it's because "two sisters married two brothers," as Atticus explains. Scout and Jem find this baffling.
What's important to note is that this particular jury member was the only one who wanted to rule that Tom was innocent, not guilty. It's ironic because the Cunninghams are the ones accusing Tom of the crime, but one of their relatives believes Tom is innocent and tries to defend him -- he was probably the reason the jury deliberated for a few hours instead of just a few minutes. Back when the jury was being assembled before the trial began, Atticus thought he'd recognized this jury member, and Atticus had the chance to strike him from the jury. He wisely chose not to do so.
In chapter 23, Atticus and Jem are discussing the Tom Robinson trial and Jem tells his father that the jury made up its mind in a hurry. Atticus disagrees with Jem's assessment and tells his son that there was one man who was "rarin’ for an outright acquittal." Atticus does not name a specific person but tells his son that it was someone from the Old Sarum Bunch. Jem is astonished and knows that there must have been someone from the Cunningham family supporting Tom Robinson on the jury. Atticus looks out of the side of his eyes and tells Jem that it was one of the Cunninghams' connections. Atticus then elaborates on the character of the Cunningham family by telling Jem that if they respected you, they were with you tooth and nail. Even though Atticus does not name a specific member of the Old Sarum Bunch, the reader learns there was at least one member of the Cunningham family on the jury.