This is one of the rarest Pioneer gold coins and also one of the most important. The 1849 Mormon issues were the first Pioneer gold coins struck from California gold. And the 1849 $20 is the largest denomination of the Mormon gold coins. But this denomination, and the even rarer 1849 $10, were struck in extremely limited quantities.
I recently examined the Smithsonian example (through a plexi-glass display case) and I believe PCGS would grade the coin MS61. It is arguably the finest known. This coin came from the incredible Lilly collection, which was donated in whole to the Smithsonian. Most of the great Pioneer gold coins in the Smithsonian are from the Lilly collection.
Discovered in a safe deposit box in 2016
Josiah Lilly - National Numismatic Collection at the Smithsonian Institution
John Glover Kellogg and heirs - Thomas Elder 10/1916:741, $450 - Virgil Brand Collection (Brand Journal #81206) - Armin Brand, offered at $600 on 3/1/1942) - B.G. Johnson - Jacob Shapiro Collection - Stack's 12/1944:1020, $900 - Major Alfred Walter Collection - New Netherlands 12/1968:593, $8,000 - Henry Clifford Collection - Kagin Collection Collection - Riverboat Collection - Heritage 4/2014:5456, $558,125
Judge Slack Collection - B. Max Mehl 5/1925:51 - Dr. Russell H. Renz Collection - B. Max Mehl 3/1948:3923 - Stack's 1/1990:332, $41,250