From "Poor Farm Cemetery, Winnebago County Wisconsin" by Eiler & Dunn (2010):
Mary died on 4 July 1894 and was buried at the Hospital Cemetery. She is 43 years old and born about 1851.
I found a death record filed for her death on 4 July 1894 in Tomahawk, Lincoln Co, WI and was buried at the Northern Hospital. This record also states she was 43 years old and born 1851 in Ireland. Her grave number is unknown.
In the 1870 Census, Mary is residing in Germantown, Juneau Co, WI with her husband, Roland, and daughters, Grace and Mary. She is 19 years old and born in IL.
In the 1880 Census, she is still residing in Germantown with her husband, Rouland Bariett, and children, Grace, Shella, Rouland, John Harry and Robert. She is 28 years old and born in Ireland.
In the 1900 Census, she is residing in the 4th ward in the City of Tomahawk, Lincoln Co, WI with her husband, Rouland Burret, and children, R.G., J.J. Harry, R.H., B.B., ?.M., and an unreadable name. Mary's age and birth date are marked unknown and she is born in Ireland.
The State of WI has two death records filed for Mary. The first one is indexed as Mary E. Burrette and the second one is indexed as Mary E. Burritt. Both have a death date of 4 July 1894 in Winnebago County.
NOTE: There seems to be a marker for Mary Burritt next to her husband in Tomahawk as well: