Rafaela Herrera died in 1805.
Rafael Ramírez Hidalgo was born in 1805.
San Rafael Department was created on 1805-04-02.
There was no 1805 British Halfcrown minted.
$100,000,000
The Sovereign was not reintroduced into the British currency until 1817.
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The coin you have described, dated 1805 with the inscription "dei gratia carolus IIII", is a Spanish colonial coin. The value of this coin can vary depending on its condition, rarity, and demand among collectors. It is recommended to have the coin appraised by a professional numismatist to determine its exact value.
An 1805 Draped Bust U.S. Large Cent, graded as MS-60 starts at $3,000.00. This value dramatically changes depending on the color, contact marks and surface condition. If the coin actually is a Mint State example it needs to be seen for an accurate assessment of the value.
The U.S. did not strike any silver dollars for circulation between 1804 and 1835 inclusive. If you have a coin dated 1805 it's a counterfeit. If you have a different date, please post a new question.
All US silver dollars are round, but none are dated 1805. Please check your coin again and post a new, separate question with more information that might help to ID it.
1805 Pattern Halfpennies (Britannia and wording BRITANNIARUM on the reverse) are extremely rare. Choice FDC (Fleur-de-coin i.e. perfect) examples can make £500 - £700. They are normally found in mint state as they were never issued for circulation. Do not get these confused with the 1805 Irish halfpenny with harp...these are worth considerably less.