Carlos Emmons - politician - was born in 1799.
The value of a 1799 coin depends on the coin's denomination such as dime or quarter. It also depends on what country the coin came from, where it was minted and the condition of the coin. Without that information, it is impossible to state a value.
Carlos IV and his family
Carlos Corpus IV goes by Chino.
Of the 4 US coins that are dated 1799 all have Liberty on them a denomination would help.
The only U.S. coin dated 1799 in the weight range, is a $10 gold eagle at 17.50 grams.
No US 1799 coin will have a mintmark, all were struck in Philadelphia.
Mission Bells: Four bells hang in the companario, one of them an original donated to the mission in 1798 by King Carlos IV of Spain, who donated a second bell in 1799. The 1799 bell was broken during the 1929 fire that destrobyed the Church.
The value would depend upon the denomination and the condition of the coin.
Try a coin dealer or take it to a coin show.
Charles IV in his Hunting Clothes is a very famous painting. It was painted in 1799 by the celebrated Spanish artist Francisco Goya, using oil on canvas.
The best choice would be to take it to a coin shop and have it appraised.