It would be a Spanish coin and you need to provide measurements or a denomination for us to know if it is an 8 reale or 1/2 reale coin or anywhere in between.
December 8 1805 was a Sunday.
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.
The CAROLUS IIII DEI GRATIA (or CAROLUS IIII DEI G) coins to which you possibly refer was a large silver Spanish-American Eight Reale (pieces of Eight) coin minted at various mints in Spain, Mexico, South and Central America. Due to a shortage of suitable metals during the Naploenic Wars, and a general shortage of circulating currency, the English acquired and countermarked the Spanish-American 8 Reale coins (and others) and used them as "Emergency Issue", referring to them as "Spanish Dollars". The Spanish-American 8 Reales coins were countermarked with a small image of George III in 1804 and circulated as Four Shillings and Ninepence until 1811. Any of these coins in any reasonable condition, as long as they are identifiable and legible, might fetch well over £100 GBP.
Jay Reale's birth name is Louis Francis Reale Jr..
Robert Reale was born in 1956.
Ceresole Reale's population is 161.
Venaria Reale's population is 34,838.
Damien Reale was born in 1981.
Attilio Reale was born in 1960.
Attilio Reale is 182 cm.
Egypt Reale is 5' 0".