You do not give any dates or detail.
Any coin with a "genuine" minting flaw would have some value, above the usual, as a collectible coin.
Genuinely flawed coins are not necessarily known about or documented until somebody turns up with one, since they are an "accident" of the minting process, and have escaped detection during quality control at the mint therefore, a valuation cannot be anticipated.
A reputable coin dealer should be able to identify and confirm the coin as genuine and make a valuation.
Flaws and errors on coins should not be confused with mutilation or mangling of the coin.
It would have been minted in Dahlonega,Georgia.
No, the first US (Federal issue) gold coin was minted in 1795 and the double eagle ($20) wasn't minted until 1850.
A privately minted silver bullion piece.
The 6 piece set has a retail value of $10.00 the 3 piece is $20.00
The bronze English one penny piece, as minted between 1971 and 1992, was 1.52 millimetres thick. The steel one penny piece, as minted since 1992, measures 1.65 millimetres in thickness.
A $2.50 gold piece minted from 1796 through 1807 weighed 4.37 grams and was 91.67% gold. One minted from 1808 through 1929 weighed 4.18 grams and was 90% gold.
You'll need to check its condition and mint mark. This page shows a range of values.
120
Please post a new question with the coin's date. Quarters have been minted in Denver for over a century.
50 Cents
It means the coin was made (minted) in Philadelphia Mint.
The echidna is on the Australian 5c piece.