Any collector value would depend greatly on when they were minted, what condition they are in, and whether they are circulated or uncirculated.
British Threepences minted from 1907 to early 1920 are made from sterling silver.
British Threepences minted from late 1920 to 1937 are made from a 50% silver alloy.
Depending on the year -
Uncirculated mint condition sterling silver Threepences might get anything from £12 to £30 GBP. Circulated sterling silver Threepences might get anything from £1 to £25 GBP.
Uncirculated mint condition 50% silver Threepences might get anything from £15 to £90 GBP. Circulated 50% silver Threepences might get anything from £1 to £35 GBP.
Pieces of Silver A Story of Hearts and Souls - 1914 was released on: USA: March 1914
Daniel Boone - 1964 Thirty Pieces of Silver 4-25 was released on: USA: 28 March 1968
Alcoa Theatre - 1957 30 Pieces of Silver 2-9 was released on: USA: 26 January 1959
The Pieces - 2014 was released on: USA: 2014
Please check again and post a new question. The U.S. didn't mint any silver dollars for circulation between 1804 and 1835 inclusive. There are however many counterfeit pieces on the market, and among those many have impossible dates or designs.
Pieces - 2012 I was released on: USA: 1 December 2012
Missing Pieces - 2012 was released on: USA: 2012
Pieces - 1997 I was released on: USA: 2 October 1997 (MicroCineFest)
Six Easy Pieces - 1977 was released on: USA: 1977
Save the Pieces - 1928 was released on: USA: 28 January 1928
Missing Pieces - 2008 was released on: USA: 1 March 2008
Rest in Pieces - 1924 was released on: USA: 2 June 1924