In 1976, a rare error occurred at the Denver Mint, where a few bicentennial quarters were struck on dime planchets (blanks). One such coin, graded MS-67 by PCGS, sold for over $18,000 in 2020.
The San Francisco Mint produced a limited number of bicentennial silver proof quarters in 1976. One such coin, graded PR-69 by PCGS, sold for $8,812.50 in 2017.
Another error coin from 1976 is the bicentennial quarter struck on a nickel planchet. These coins are extremely rare and can fetch prices well over $10,000.
A double die error occurred on some 1976 bicentennial quarters, where the image on the obverse side was struck twice, creating a distinct doubling effect. One such coin, graded MS-66 by PCGS, sold for $7,637.50 in 2019.
Occasionally, a bicentennial quarter was struck on a 40% silver planchet intended for Eisenhower dollars. These coins are highly sought after by collectors and can command prices exceeding $10,000.
Some bicentennial quarters exhibit a die clash error, where the reverse design of an eagle's head appears to be "spitting" because of a clash with the obverse die. These error coins can sell for several thousand dollars.
A few bicentennial quarters were mistakenly struck on planchets intended for regular Washington quarters, which are composed of a copper-nickel alloy. These coins are rare and can be worth over $5,000.
Bicentennial quarter proofs with deep cameo contrast between the design elements and the fields are highly desirable among collectors. A proof 1976-S bicentennial quarter graded PR-69 by PCGS sold for $6,463 in 2018.