Standing Liberty Quarter
Liberty stands in a gateway between two pillars, holding a shield in one hand and an olive branch in the other, with the date on the pedestal below. An eagle flies right surrounded by stars, with UNITED STATES OF AMERICA above and QUARTER DOLLAR below.
Composition
Key dates to look for
1916 Standing Liberty
$3,000+ even heavily wornFirst year, only 52,000 made — the key to the whole series
1921 Standing Liberty
$150 – $300 in worn gradesLow mintage of 1.9 million
1923-S Standing Liberty
$250 – $500 in worn gradesOnly 1.36 million made
1927-S Standing Liberty
$30 – $75 worn, $1,000+ lightly circulatedJust 396,000 made; cheap worn but very expensive in high grade
Valuable varieties & errors
1918/7-S Overdate
extremeA die was hubbed first with a 1917 date and then with a 1918 date, leaving the 7 visible underneath the 8. It is one of the most famous overdates in all of US coinage.
Error types found on this series

Doubled Die (Obverse)
The front design shows a second, shifted image because the die itself was made doubled.

Die Crack
A crack in the die fills with metal during the strike, leaving a thin raised line on the coin.

Clipped Planchet
A bite-shaped piece of the coin is missing because the blank was punched from an already-punched part of the metal strip.

Off-Center Strike
The blank wasn't centered when struck, so part of the design is missing and part of the coin is blank.

Lamination Error
A thin layer of the coin's metal peels, flakes, or cracks off because the alloy was poorly mixed.
Real photos where available (credits); others are illustrations.