I found the James and Ann Sampson and family in 1850 in Shullsburg, Lafayette Co., Wisconsin.
James Sampson, b. England, 31, miner.
Ann, wife, b. England, 29.
William, b. England, 12.
Charles, b. England, 11.
Mary, b. England, 8.
Jane, b. England, 6.
Elisabeth, b. WI, 1.
Then in 1860 the family was living in Placerville, El Dorado Co., CA.
James Sampson, b. England, 44, farmer.
ann, wife, b. England, 43.
William, b. England, 22, teamster.
Charles H., b. England, 21, miner.
Jane, b. England, 16.
Elizabeth, b. WI, 12.
Ellen, b. Utah Terr, 6.
Emily, b. CA, 2.
Is this the correct family?
In the 1857 Marysville Directory a Chas. Sampson "boards at Haun House".
Wm. H. Sampson, dwelling E between Second and Third, Eng. Source: yubaroots.com/directories/1856ce.htm .
There is a partial database of deaths prior to 1905 (when the State required death certificates).
William Henry Sampson, b. 1811, died Nov. 29, 1864, born=Beverly, Yorkshire, England, buried Marysville. No record for Charles.
Source: Death records Prior to 1905, yubaroots.com/deaths/di-sa.htm.
Tell me if I have found members of your family and I'll pursue.