Her will was proved in 1823 but no record can be found of any burial in that year.  Why not?

But…  Her almost certain burial, noting her longevity:

First name(s)   Mary
Last name       Jaques
Age             89
Birth year      1734
Residence       Castle St
Marital status  widow
Death year      1823
Burial year     1823
Burial date     09 Oct 1823
Church          St Peter
Place           Wallingford
County          Berkshire
Country         England
Record set      Berkshire Burial Index
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A will has been found in PCC for ‘Widow of All Hallows Wallingford , Berkshire’ dated 14th November 1811 and proved on 20 October 1823.  Ordered and received on 16 March 2020.

In her will she lists:

‘My  son-in-law Charles greenwood’,
‘My son Greenaway Jaques’,
‘My daughter mary Ann (wife of the said Charles Greenwood)’,
‘My granddaughters Mary Ann and Phillis (daughters of Ann the said Charles Greenwood)’ [sic],
‘My grandson William Jaques (son of him the said Greenaway Jaques [)]’,
‘and Elizabeth (the late wife of Thomas Greenwood)

She appointer Charles Greenwood and Greenaway Jaques her executors.  Though only Charles G survived until 1823.
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From Family Search:

spouse:                          Mary Wheeler
Name                             Greenway Jaques
Spouse's Name                    Mary Wheeler
Event Date                       11 Jul 1769
Event Place                      Hampshire
Spouse's Previous Husband's Name
Indexing Project (Batch) Number  I03915-1
System Origin                    England-EASy
GS Film number                   1278952

Why isn’t the parish known?
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And Sarum Marriage Licence Bonds gives:

First name(s)           GREENAWAY
Last name               JAQUES
Birth year              -
Bond day                11
Bond month              Jul
Bond year               1769
Marriage year           1769
Place                   WALLINGFORD ST PETER
Groom's first name(s)   Greenaway
Groom's last name       JAQUES
Groom's age             -
Groom's occupation      bargemaster
Groom's parish          Wallingford St Peter
Groom's county          Berkshire,England
Bride's first name(s)   Mary
Bride's last name       WHEELER
Bride's age             -
Bride's parish          Wallingford St Leonard
Bride's county          Berkshire,England
Bondsman 1              WHEELER Henry,curier,Wallingford St Peter
Jurisdiction            The Bishop of Salisbury in Wiltshire and Berkshire
County                  Berkshire
Country                 England
Record set              Sarum Marriage Licence Bonds
Category                Birth, Marriage, Death & Parish Records
Record collection       Marriages & divorces Collections from Great Britain
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