Original meaning
Originalists of all stripes cite "The Federalist Papers". It is fairly tenuous to suggest that this represents a good source for the original "intent": after all, Alexander Hamilton, who wrote the majority of those essays, was absent for the greater part of the Philadelphia Convention, and John Jay did not attend it at all. However, James Madison, the principal framer of the Constitution also wrote a substantial amount of "The Federalist Papers". Also, to suggest Hamilton and Jay's absence from the convention implies their ignorance as to the Constitution's original meaning is demeaning to those two men and inaccurate. The collected anti-Federalist papers, of course, will be no use at all to a person searching for the original "intent" of the framers. However, as evidence of how a reasonable person at the time would have understood the words of the Constitution, "The Federalist Papers" and the anti-Federalist essays are evidence of direct relevance.
Federal Farmer
Surviving private correspondence is unhelpful in answering the question of authorship. Many contemporary writers admitted the author's identity was unknown to them, including Noah Webster, Timothy Pickering, and Edward Carrington, who was in New York with Lee at the time the pamphlets were composed. Lee was not the only writer accused by Federalists of producing the pamphlets—a correspondent of John Lamb accused him of diverting money from the New York impost into the production of "the foederal farmer and other false Libels." Historian Gordon S. Wood observes that at least in Connecticut, emphasizing the association of Lee with any Anti-Federalist production would have been a sound political move for the Federalists; the Lee family was reviled in the state due to the involvement of Arthur Lee, Richard Henry's brother, in instigating the recall of Connecticut merchant Silas Deane from his position as envoy to France.