Name, estimated year of birth as circa 1839, place of birth as "Devon, England" from 1841 England Census for Civil Parish of Pyworthy, Holsworthy, Devon. A link to this was received from Katia, wife of Tim Grant Oliver, in an email dated 19 December 2022:
Mary Oliver, F, age 2, Born Devon England [circa 1839]

Estimated year of birth as circa 1840, place of birth as "Pyworthy, Devon, England" 1851 England Census for the Parish of Pyworthy, Milton Damerel, Devon, England found in January 2023:
House at "Bounds Cross":
Mary H [?] Oliver, Daughter, F, age 11, Scholar, Born Pyworthy Devon England [circa 1840]
Looking at the 1841 and the 1851 Censuses above, one places the estimated year of birth as circa 1839 the other circa 1840. For now we will place year of birth as circa 1839.

For full family details of the above Censuses, please see personal page of either parent.