Her grave markern states
"Wife of John Ellison, Aged 71 yrs" making her born about 1844. The date I use is from the 1900 census see below.
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Note from Tex is that census records would put her birth at about 1850 by the 1860 census she is 10 years of age. I can't find the family on the 1850 census.

Her correct married name should be Allison but John Allison / Ellison unable to read or write might not have known that it was Allison and when someone put Ellison he was unable to correct it. The name has since 1880 been Ellison but only in John's line as all others still use Allison. See below data.
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1850 GA, Habersham
J C C Allison Age: 3 Birth Year: abt 1847
Birthplace: Georgia Home in 1850: District 8, Habersham, Georgia
Gender: Male Family Number: 36 Household Members:
Name Age
Thos Allison 26
L J Allison 26
N Allison 11
W T Allison 9
G L Allison 7
R J Allison 5
J C C Allison 3
B P Allison 0
http://search.ancestry.com/cgi-bin/sse.dll?db=1850usfedcenancestry&indiv=try&h=18702187
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1860 GA, Lumpkin Co., Frogtown
Thomas Allison Age in 1860: 37 Birth Year: abt 1823 Birthplace: North Carolina
Post Office: Loudsville
Household Members:
Name Age
Thomas Allison 37
Mary A Allison 22
Noah Allison 22
William F Allison 20
Lafayett G Allison 18
Rosettee J Allison 16
John C H Allison 14
Benjamin P Allison 12
James M Allison 10
Robert M Allison 6
Lewis E Allison 3
http://search.ancestry.com/cgi-bin/sse.dll?db=1860usfedcenancestry&indiv=try&h=11373732
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1870 GA, Union Co., Subdivision 126
John Allison Age in 1870: 21 Birth Year: abt 1849 Birthplace: Georgia
Post Office: Blairsville
Household Members:
Name Age
John Allison 21
Celia J Allison 21
Jasper T Allison 5
Georgia C Allison 2
http://search.ancestry.com/cgi-bin/sse.dll?db=1870usfedcen&indiv=try&h=6729783
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1880 GA, Milton Co., Little River
John Elison Age: 33 Birth Year: abt 1847 Birthplace: Georgia
Relation to Head of House: Self (Head)
Marital Status: Married Spouse's Name: Celia Elison
Father's Birthplace: Georgia
Mother's Birthplace: Georgia
Household Members:
Name Age
John Elison 33
Celia Elison 27
Georgia C. Elison 12
John S. Elison 8
Mary L. Elison 6
Sarah C. Elison 1
http://search.ancestry.com/cgi-bin/sse.dll?db=1880usfedcen&indiv=try&h=8829610
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1900 GA, Cobb Co., ED# 40, 911 District Gritter page 180, pix of census in folder.
John Ellison Age: 60 Birth Date: Feb 1840
Birthplace: Georgia [Cobb] Race: White Gender: Male
Relation to Head of House: Head Marital Status: Married
Spouse's Name: Celia J Ellison Marriage Year: 1864 Years Married: 36
Father's Birthplace: Georgia
Mother's Birthplace: Georgia
Household Members:
Name Age
John Ellison 60 Feb 1840?
Celia J Ellison 48
Fate Ellison 13
Mintie C Ellison 11
Mattie Mcintire 63 his sister-in-law
http://search.ancestry.com/cgi-bin/sse.dll?db=1900usfedcen&indiv=try&h=8541334
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1900 - GA, Cobb Co., Gritter, He was born Feb 1840 in GA is a farmer and married 36 years both parents born in GA. Ceclia Jane is named as his wife born Jan. 1852 in GA age 48 years has 7 of 7 children living her father born SC and her mother born NC she has been married 36 years. In this HH is Fate? his son born June? 1886 15 years old then what looks like Minne L or E daughter born July 1889 is 11 years old no other children listed but a sister-in-law is and her name is Mattie McEntire? born March 1837 is age 83 single father born SC mother born NC

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1912 about Georgia, Confederate Pension Applications, 1879-1960
about John Ellison
Name: John Ellison
County: Cobb
Approx. Application Year: 1912
Application Type: Soldier
Archive Collection Name: Pension Applications of Confederate Soldiers and Widows
Archive Collection #: GCP-092
Number of Images in Packet: 4
http://search.ancestry.com/cgi-bin/sse.dll?db=GAconfederatepension&h=42903&indiv=try&o_vc=Record:OtherRecord&rhSource=7602
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1910 - GA, Cobb Co., District 35 MD No. 851 - Acworth, excluding Acworth town
John Ellison Age: 69, white Male born GA,
pix in folder
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Census Microfilm Records: Georgia, 1900 Lived in: 991 Militia District, Cobb County, Georgia Series: T623 Microfilm: 189 Book: 1 Page: 200

Go to Page Data Introduction John F. Ellison found in:
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Census Microfilm Records: Georgia, 1900 Lived in: Falling Water District, Habersham County, Georgia Series: T623 Microfilm: 202 Book: 2 Page: 16 Go to Page Data Introduction John Ellison found in:
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Marietta City Cemetery , Powder Springs Rd, just south of South Marietta Parkway.
John Ellison Nov. 6, 1836 - Dec. 31, 1920
Cele Jane wife of John Ellison d. July 26, 1917, aged 71 yrs.
Homer Ellison June 18, 1892 - July 19, 1929
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also in this cemetery is the
Rev. Francis Cook b. near Camden, S. C., Feb. 17, 1798 d. Marietta, GA., Mar. 10, 1872
Margaret M. wife of Rev. Francis Cook dau. of John Ellison b. near Charleston, S. C., Feb 6, 1808 d. Aug. 1, 1871

City Cemetery in Marietta, Georgia is also referred to as Citizen's Cemetery and as Marietta City Cemetery. Many of the prominent early residents of Cobb County, and particularly Marietta, are buried there.
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ELLISON, John T. 17 Oct 1919 Cobb 14973-A

1920 - Cobb Co., Death index
ELLISON, Homer 9 Jul 1929 Cobb 17990-K
ELLISON, William C. 29 Mar 1929 Cobb 07451-K
MCENTYRE, Earl 04 Nov 1920 Cobb 30839-B
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Marietta Journal & Courier November 9, 1917 From the Marietta Journal & Courier dated Friday, November 9 1917: Mr and Mrs John ELLISON are in South Georgia on a visit to relatives. Mr ELLISON has sold his farm here and probably besides visiting he had gone to see the country and if he locates there Cobb county will lose one of its best citizens.
http://ftp.rootsweb.ancestry.com/pub/usgenweb/ga/cobb/newspapers/ kennesaw2470gnw.txt
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This is what makes Find A Grave such a great place to meet new kin folks.
Tom saved the day for me with his below suggestion.
Tex
I see that this listing was transferred to you, are you kin and are you familiar with the change in names? John's father was Thomas Allison #31002683 and mother was Louiza Jane Owens # 50532276 and he was born in Habersham County(later White). The family name in NC was Allison and when they came to GA the census taker recorded them as