In 1999, some 1999-P $1 Susan B. Anthony Dollar coins were mistakenly made on the planchet for the Sacagawea dollar coins and are now worth nearly $12,000.
These coins are called transitional planchet error coins and are highly sought after.
A recent sale of one of these coins was for $11,700 at a Heritage Auction in December 2022.
To determine if you have this error coin, you should check if your gold-colored coin is dated 1999, features Susan B. Anthony, and is ranked MS65 or higher in quality.
Other valuable error coins include those with the wrong die, design, or elements of another coin.
A mule penny with the reverse design of a dime sold for $66,000.
A 2000 Sacagawea coin with the obverse of a quarter could be worth over $100,000.
A 1970s quarter minted on the planchet of a late 19th-century gold coin sold for $93,000.