Well, if the half-sovereign was brass, it is a copy and not worth anything. If it is genuine, it would be struck in gold. Bids on Ebay are around anywhere from 310 British Pounds ($447 USD/CAD, about 333 Euros) to 595 pounds ($915 USD/CAD, about 683 Euros). But keep in mind, if the coin is brass or is stamped "COPY" anywhere on the coin, it is a reproduction and not worth much of anything. Also, if you have any doubts to the authenticity of your coin, take it to a reputable coin dealer and he should be able to tell you if it is genuine or not.
Please look at the coin again, no U.S. one dollar coins are dated 1819.
The first $1 silver certificates were issued in 1886. Anything dated 1819 is a fantasy piece or an intentional fake.
There were only two 1819 coins minted with that exact inscription. The 1819 Crown (Five Shillings) with the Regnal date of LIX (in Roman numerals) along the edge and the 1819 Crown (Five Shillings) with the Regnal date of LX (in Roman numerals) along the edge. These were amongst the first Crown coins to be minted after the Recoinage act and were minted to the new standard of .925 fine silver, weighed 28.2759 grams and were 37.6mm in diameter. Some of the coins with the LX Regnal date, were minted without a fullstop after TUTAMEN. The reverse features Benedetto Pistrucci's St. George and the dragon in what could almost be called a cartwheel design. The inscription around the reverse is "HONI SOIT QUI MAL Y PENSE" meaning "Evil to him who thinks evil". The 1818 to 1820 Crown coins were the first to have been minted since 1751, and were also made from silver equal to less than the face value of the coin for the first time.
35 to 40 dollars
What country? What denomination? Please post a new question with enough details to ID the coin.
George Garth died in 1819.
George Dundas was born in 1819.
George Cornewall died in 1819.
George Uppleby was born in 1819.
George Salmon was born in 1819.
George Brimley was born in 1819.
George Denman was born in 1819.