William J Bopp married Mary Elizabeth King daughter of Daniel King & Clara Palmer Hicks King and is confirmed in numerous Ancestry.com family trees.

You have identified Mary Eleanor King daughter of Edwin & Ruth King. Edwin is Daniel Kings brother (both are sons of Henry & Elizabeth King who I challenged you as having wrong information on yesterday). Both had daughters born about the same time-Mary Elizabeth in Nov 1879 and Mary Ellen in Jan 1880.

This is the 1880 Census for Mary Ellen showing her father was born in Ohio and her mother was born in Iowa:

Database online.
East Waterloo Township (outside), Black Hawk, Iowa, ED 51, roll T9_327, page 470.3000, image 0562 sheet 7 6/1/1880

Edwin T King Age 30 (1850) Farmer b. Ohio Father b. England, Mother b. England
Ruth King Age 21 (1859) b. Iowa Father b Ohio Mother b. Ohio
Gracie A King Age 2 (1878) b. Iowa Father b. Ohio, Mother b. Iowa
Mary Ellen King Age 5/12 (Jan, 1880) b. Iowa Father b. Ohio, Mother b. Iowa

This is the 1880 Census for Mary Elizabeth King showing both her parents were born in England:

Database online
Mount Vernon Township, Black Hawk County, Iowa, District 55, roll T9_327, page 515.2000, image 0651. 6/11/1880 Page 18

William Hicks Age 73 (1807) Farmer b. England Father b. England, Mother b. England
Grace Hicks wife Age 70 (1810) b. England Father b. England, Mother b. England

Daniel King Age 32 (1848) Farmer b. England Father b. England, Mother b. England
Clara King wife Age 23 (1857) b. England Father b. England, Mother b. England
Mary E King daughter Age 6 Months (Nov 1879) b. Iowa Father b. England Mother b. England

Henry King Age 64 (1816) b. England Father b. England, Mother b. England Blacksmith
Elizabeth King Age 64 (1816) b. England, Father b. England, Mother b. England
Ada King Age 23 (1857) b. Ohio Father b. England, Mother Born England.

Alfred King Age 37 (1843) b. England, Father b. England, Mother b. England Farmer
Elva I King wife Age 24 (1856) b. Iowa Father b. NY Mother b. NY

This is the 1920 Census for Mary E Bopp showing both her parents were born in England and thus confirming that you have the wrong middle name and parents listed:

Database online
Mount Vernon Township, Black Hawk County, Iowa, District 55, roll T9_327, page 515.2000, image 0651. 6/11/1880 Page 18

William Hicks Age 73 (1807) Farmer b. England Father b. England, Mother b. England
Grace Hicks wife Age 70 (1810) b. England Father b. England, Mother b. England

Daniel King Age 32 (1848) Farmer b. England Father b. England, Mother b. England
Clara King wife Age 23 (1857) b. England Father b. England, Mother b. England
Mary E King daughter Age 6 Months (Nov 1879) b. Iowa Father b. England Mother b. England

Henry King Age 64 (1816) b. England Father b. England, Mother b. England Blacksmith
Elizabeth King Age 64 (1816) b. England, Father b. England, Mother b. England
Ada King Age 23 (1857) b. Ohio Father b. England, Mother Born England.

Alfred King Age 37 (1843) b. England, Father b. England, Mother b. England Farmer
Elva I King wife Age 24 (1856) b. Iowa Father b. NY Mother b. NY

The above genealogical research was provided courtesy of Find A Grave member Ross Morton. Thank you