1804 dollar is one of the great rarities in US numismatics. One is worth whatever it brings at auction, most likely into the millions. It is also one of the common cheap Chinese counterfeits, if you have one it is almost certainly the latter.
Not trying to buy or sell. She said it was located with a PCGS case but it had gotten wet and weathered. Unreadable. I have to agree with that as the S and part of the G were legible.
There are 15 vintage 1804 dollars and literally MILLIONS of modern copies. The Chinese are not only producing fake collector-coins, they are also producing fake slabs -- so a slab means nothing unless it can be corroborated with the slabbing company. Of the 15 vintage 1804 dollars, seven (I believe) were struck in 1834 and the rest were struck in the 1860's and 1870's. Smithsonian has three of them. 'Recent' auction records run around five million dollars or so. The most readily available LEGAL 1804 dollars are from the Gallery Mint, now after-market items available in either Unc or Proof. They are punched 'COPY' on either front or back.
Here's a listing of auction prices: https://www.pcgs.com/auctionprices/details/1804-original-class-pr/6907. Hope you're not thinking of buying one listed on a website. When they do sell it's usually at a major auction.