The origin of Sunnyside Cemetery is for the most part hidden, but earliest records date back to 1846. On October 29, 1846, the Southeast 1/4 of the Southeast 1/4 of Section 8 in the town of Menomonee was deeded to Joel Bancroft. All of Sunnyside Cemetery is still in this parcel of land. The first burial was Betsy Waterman, age 32, who died in 1847. She is not buried near the Bancroft lots so it is assumed that she was not related to them. Joel Bancroft died in 1848. In December of 1848, this parcel was sold to Abner Rowe who sold it to Daniel and Charity Smith in May of 1851.
On March 3, 1855, the Menomonee Center Cemetery Association was organized. There were seven recorded burials prior to this date and from their locations it is obvious that the cemetery was platted out at some prior time, although there is no record of a cemetery being in any of the deeds or abstracts for this parcel of land.
On January 3, 1862, one acre comprising the original plat was deeded to the Menomonee Center Cemetery Association by Daniel and Charity Smith. On October 1, 1888 Daniel Smith’s son, George and his wife, Elizabeth deeded the First Addition to the cemetery. This is the area from the big maple trees down Main Street, then known as Waukesha Road.
In June of 1892, the name of Menomonee Center Cemetery Association was changed to Menomonee Union Sunnyside Cemetery and in June of 1894 changed again to Menomonee Sunnyside Cemetery. Later in 1894 it was re-named again to Sunnyside Cemetery, which has remained the name to present day. In 1898, a narrow strip of land on the south and west sides containing a row of maple trees was sold to the cemetery for $1.00 by George and Elizabeth Smith.
In 1922, a 1 1/2 acre strip of land on the north side was purchased from Nicholas and Anna Lauer, and in 1960 a 4.022 acre parcel on the south and west side was purchased from Alvin and Charles Smith. 
It was discovered that both the State of Wisconsin and Waukesha County claimed to have no record of the cemetery being organized or incorporated, so on February 24, 1975 the Sunnyside Cemetery Association was re-organized and incorporated in accordance with the regulations of the State of Wisconsin.
Old records in the cemetery’s possession indicate that the incorporation of the Menomonee Center Cemetery Association of March 3, 1855 was indeed recorded in Vol. 1, page 37 by Wm. R. Williams, Register of Deeds, Waukesha County on March 28, 1855.
As of April 15, 2000, Sunnyside Cemetery contains 2278 burials with probably a few more early burials in unmarked graves or those where stones were broken off. The early 21st century brought about the most recent parcel of cemetery that was purchased from Charles and Elizabeth Smith. 9.6 acres of field from behind the garage to the surrounding tree line on the west and north sides is currently being surveyed and developed.
