More information is needed - is it a British penny or American cent?
Please post a new, separate question with the name of the country that issued the coin.
A US Large Cent dated 1797 would be a Draped Bust cent. Type this info into your search box and click images.
what is the value of a 1903 indianhead penny
what is the value of 1945d penny
what is the value of a 1912 lincoln wheat penny
...If you can read the date on the penny, it is not an unstamped penny.
The British "Cartwheel Penny" and "Cartwheel TwoPence" were only issued in 1797. The Isle of Man "Cartwheel Penny" and "Cartwheel Halfpenny" were issued in 1798 and 1813. Any of these coins in excellent condition could be considered valuable.
The British 1797 "Cartwheel" Proof Penny was minted in a variety of metals including, Gilt copper, Copper, Bronzed, Silver and Gold. Mintage figures are not given since coins from this period were usually produced by a specific weight, ie. two tonnes of Pennies. Most of the 1797 Proof coins are rated as various degrees of "rare".
Your coin is either a British 1797 "Cartwheel" Twopence 41mm in diameter, or a British 1797 "Cartwheel" Penny 36mm in diameter. If somebody has drilled a hole in it, it might be worth a few Pence. Modified coins have no collector value.
The British 1797 Penny does not have stars on it. Due to Britains ongoing expenses with various wars in the late 18th and early 19th centuries, there were very few silver or copper coins minted, subsequently there were a great many privately minted tokens and counterfeit coins produced. To get an estimate of value on a privately minted token, you need to provide the details of the inscription on the token.
A US Large Cent dated 1797 would be a Draped Bust cent. Type this info into your search box and click images.
If you refer to the British 1797 Penny and Twopence coins, they may have been cursed by the people who had to use them. Both coins were very big and very heavy, even by the standards of the day. The 1797 "Cartwheel" Penny weighed 1 ounce or 28.35 grams and was 36 mm in diameter. The 1797 "Cartwheel" Twopence weighed 2 ounces or 56.7 grams and was 41 mm in diameter.
The only British copper coins minted in 1797 were the Cartwheel Penny and the Cartwheel Twopence. They were referred to as "Cartwheel" coins because of the distinctive rim around the edge of the coins giving the appearance of a cartwheel. Exact mintage figures can only be guessed at since the mintage for 1797 was referred to in tons of coins. There was a combined mintage of 5 tons of British Penny and Twopence coins minted in 1797. These were the first British copper coins to have been minted in over 20 years. The 1797 Penny weighed 1 ounce or 28.35 grams. The 1797 Twopence weighed 2 ounces or 56.7 grams.
what is the value of a 1903 indianhead penny
what is the value of 1945d penny
what is the value of a 1912 lincoln wheat penny
If you refer to the GEORGE III 1797 "Cartwheel" Penny and Twopence, they are both made from copper and are of almost identical appearance, the Penny is a little over 30 mm in diameter and the Twopence is much larger at about 40 mm in diameter.
This is not enough information to give an accurate value amount. Need to know 'Type' of penny, 'Date' of penny and 'condition' of penny.