$20 National Bank Note. National Mount Wollaston Bank, Quincy, MA. Ch. 517. Fr. 494. PMG Very Fine 20. This bank operated as the Mount Wollaston Bank prior to the National Bank era, and issued what we today call Obsolete notes. Once this bank chartered in September 1864 it would almost last the entire aforementioed era before being liquidated on the last day of 1934. This is the only known $20 Brown Back on the bank and is problem-free. PMG graded Very Fine 20. Estimated Value $750 - UP