Ron Guth: The 1818/5 Quarter Dollar is one of ten die vareities of the year, and it is the only one which shows an overdate. In it's first use (Browning 1), the obverse die shows clear remnants of a 5 beneath the second 8 of the date, as well as evidence of clashing from the reverse scroll that shows up as a line connecting the tops of the digits of the date. Later, the die was polished to remove the underdate, then the die was used again (Browning 3) with a different reverse.
The 1818/5 Quarter Dollar is a fairly common variety and can be found in high grade. According to the Rea-Koenings-Haroutunian census, the top ten examples range in grade from MS-65 to MS-67. The PCGS CoinFacts Census ranges from MS-65 to MS-66. The difference between the two censuses is the Browning plate coin (ex Col. Green, now in the Eric P. Newman collection) -- graded MS-67 by Rea et al.
James A. Stack Collection - Stack’s 3/1975:14 - RARCOA “Auction ‘90” 8/1990:640 - D. Brent Pogue Collection -Stack’s/Bowers & Sotheby’s 5/2015:1059, $49,937.50
"Colonel" E.H.R. Green Collection - Partnership of Eric P. Newman & B.G. Johnson (St. Louis Stamp & Coin Co.) - Eric P. Newman, who paid $10 - Eric P. Newman Numismatic Education Society - Heritage 11/2013:33336, $176,250 - Oliver Jung Collection - Heritage 8/2014:5569, $182,125
Col. E.H.R. Green Collection - Numismatic Gallery 8/1946:418, $33 - John Jay Pittman Collection - David Akers 5/1998:1271, $40,700 - D. Brent Pogue Collection - Stack's/Bowers & Sotheby's 5/2015:1058, $32,900