According to their web cite, Fairmount Park, covering 9,200 acres, is one of the largest urban parks in the country. It is comprised of 62 regional and neighborhood parks, the largest of which are East and West Park, F.D.R. Park, Tacony Creek park, Pennypack Park, and Wissahickon Park. When I say Fairmount Park, I'm only referring to the original, basic park areas on both sides of the Schuylkill River, East and West Parks. I'm not sure how big of an area that is, probably about 3,000 acres or so. It's still a big section of park. It's been a park for a long time. It's where they held the Centennial Exposition in 1876 and Memorial Hall from the Exposition still stands. There are several colonial mansions around the park, many football, baseball, rugby, soccer fields, driving ranges, golf courses and many picnic areas. Boathouse Row is right along the river. They hold several regattas there annually.
To answer your question, my count on silver pieces found in East and West Fairmount Park, is 4,243. This includes everything from 3 cent pieces to silver dollars. And I'm not kidding when I say that similar totals were probably found by many of the regular hunters of the park.