Joseph Sedgwick  [parents unknown]
b. March 11, 1815, Durham, England1a
d. March 17, 1882, Portlandville (now Akron), Plymouth, Iowa1a
m. September 23, 1846, Grant County, Wisconsin, Hannah Peacock3

Hannah Peacock  [parents unknown]
b. December 28, 1823, Yorkshire, England1a
d. June 16, 1874, New Diggings, Lafayette, Wisconsin1a
bu New Diggings, Lafayette, Wisconsin, Shawnee Cemetery (near her son "Sid")1a

Census Records:

1850 WI Lafayette, New Diggings
1860 WI Lafayette, New Diggings
1870 WI Lafayette, New Diggings
1880 WI Lafayette, New Diggings

Joseph Sedgwick was said to have worked as a miner in England. He immigrated to the U.S. at the age of 22 in 1837, moving first to Pennsylvania, then in 1838 to Missouri and in 1839 to Shullsburg, Wisconsin. He moved to New Diggings, Lafayette, Wisconsin in 1841, and made a claim of 10 acres which he built over the years into 280 acres. Served as school director and a member of the town board. It is believed that he is buried in Shawnee Cemetery, New Diggings near the grave of his son "Sid" and his wife.

Children:

William Sedgwick
  b. August 12, 18471a
  d. At Birth1a
Thomas Sedgwick1a
  b. July 7, 18481a
  d. May 17, 19221a
  m. July 8, 1870, New Diggings, Lafayette, Wisconsin, Sarah Ann Edge2,4
Joseph Sedgwick1a
  b. November 22, 18501a
  d. May 12, 18681a
John William Sedgwick1a
  b. January 28, 18531a
  d. August 15, 19251a
George Sidney Sedgwick1a
  b. March 20, 18551a
  d. August 16, 19351a
  m. April 9, 1881, Grant County, Wisconsin, Barbara E Richardson3
Elizabeth Ann Sedgwick1a
  b. February 4, 18581a
  d. June 14, 19291a
  m. Peacock1a
Sarah Jane Sedgwick1a
  b. February 4, 18581a
  d. December 3, 19251a
  m. Carpenter1a
Hannah Emeline Sedgwick1a
  b. April 28, 18611a
  d. January 29, 19271a
  m. Agnes1a
Ruth Etta Sedgwick1a
  b. May 20, 18631a
  d. September 7, 19351a
  m. Callan1a
Joseph Alonzo Sedgwick1a
  b. June 15, 18671a
  d. February 27, 19481a

If you can get to South Dakota, you can read more about Joseph Sedgwick here:

Genealogy Charts: Joseph Sedgwick, of England and Lafayette County, Wisconsin
  Collection of Genealogy Charts (155pg) by Betty Jane Sedgwick, 1974
  at the South Dakota State Archives Main Collection

Notes for later use:

Ancestry.com: Iowa Cemetery Records
NameDeath DateBirth DateCemeteryTownAdditional Details (Including Relatives)Level Info
Thomas Sedgwick17 May 1922 07 Jul 1849Grace HillHawarden(Hawarden Chron. 18 May 1922) Bk 21, Lot 5;wif: Sarah A. EdgeCemetery Records of Sioux County
Sarah Ann Sedgwick01 Sep 192127 Dec 1849Grace HillHawardenBk 21, Lot 5Cemetery Records of Sioux County

Sources:

1. Records of descendants and researchers
a. Todd Temperly, great-great-grandson of Joseph Sedgwick and Hannah Peacock
    Todd used to have a website with all this information, now disappeared.

2. Census Records, any of those indicated

3. Wisconsin Marriages, 1835-1900
an Ancestry.com database
These records:
NameSpouseMarriage DateCountyState
Joseph SedgwickHannah Peacock23 Sep 1846GrantWI
George Sidney SedgwickBarbara Richardson9 Apr 1881GrantWI

4. Wisconsin Marriages, pre 1907
an Ancestry.com database
These records:
NameMarriage DateCountyVolumePage
Thomas Sedgwick08 Jul 1870Lafayette010415
Sarah Ann Edge08 Jul 1870Lafayette010415

Questions? Have more data? genealogy@sedgwick.org