The identity of James Harris (28) is fairly well established including his baptismin Dodderhill.
The baptism register gives James' parents as William and Mary Harris resident in St Nicholas Droitwich.
When James and Christiana married James was a Bricklayer.
James is not with his parents in the 1841 Census.
There are several William Harris and Mary in Worcestershire around this time, but only one in Droitwich where James was born.
Thus the marriage of William harris to Mary Harrison looks most likely but has no supporting evidence.
Several potential baptisms have been identified for both William and Mary.

Therefore the identity of William and Mary as James' parents is fairly certain.
The fact that she was Mary Harrison is likely.
Their earlier identity is unknown as yet.
  

Mary Harrison	16 Feb 1796	ST ANDREW,DROITWICH,WORCESTER	John Harrison, Sarah		
Mary Harrison	06 Mar 1796	INKBERROW,WORCESTER	James Harrison, Ann		
Mary Harrison	10 Mar 1796	BROMSGROVE,WORCESTER	Thomas Harrison, Mary		
Mary Harrison	27 Mar 1796	Bromsgrove, Worcester	Thomas Harrison, Mary		
Mary Harrison	27 Apr 1796	ST ANDREW,DROITWICH,WORCESTER	Winter Harrison, Mary	death:	03 Feb 1797
Mary Harrison	04 Sep 1796	SAINT PETER,DROITWICH,WORCESTER	George Harrison, Elizabeth		
Mary Ann Harrison	05 Jan 1799	INKBERROW,WORCESTER	Thos. Harrison, Maria		
Mary Harrison	30 Mar 1799	NORTH AND MIDDLE LITTLETON,WORCESTER	Richard Harrison, Mary		
Mary Harrison	03 Aug 1799	DODDERHILL,WORCESTER	William Harrison, Hannah		

There is insufficient information to make a decision on which of these, if any, might be Mary (57).

Mary Harris baptisms for this period.					
Mary Harris	06 May 1798	Old Swinford, Worcester	Henry Harris, Elizabeth		
Mary Harris	18 Mar 1798	GREAT KYRE,WORCESTER	William Harris, Elizabeth		
Mary Harris	06 May 1798	OLD SWINFORD,WORCESTER	Henry Harris, Elizabeth		
Mary Harris	07 Nov 1797	Old Swinford, Worcester	Edward Harris, Theodosia		
Mary Harris	01 Jan 1797	OVERBURY,WORCESTER	John Harris, Mary		
Mary Harris	05 Mar 1797	OLD SWINFORD,WORCESTER	William Harris, Mary		
Mary Harris	12 May 1799	SALWARPE,WORCESTER	William Harris, Elizabeth		
Mary Ann Harris	12 Feb 1797	HALESOWEN,WORCESTER	Thomas Harris, Ann		
Mary Ann Harris	25 Aug 1799	HALESOWEN,WORCESTER	Andrew Harris, Hannah		
Mary Harris	27 Mar 1800	Old Swinford, Worcester	Thomas Harris, Nanny		
Mary Harriss	01 Apr 1796	Bromsgrove, Worcester	Thos. Harriss, Eleanor		
Mary Harriss	30 Mar 1800	Pedmore, Worcester	James Harriss, Elizabeth Harriss		
Mary Ann Harris	20 Mar 1796	Pedmore, Worcester	Eliz. Harris		
Mary Harris	26 Jun 1796	ST GEORGE-RC,WORCESTER,WORCESTER	John Harris, Eliz.	birth:	16 Jun 1796
Mary Harris	16 Jul 1800	LINDRIDGE,WORCESTER	Richd. Harris, Eliz.		
Mary Ann Harris	20 Mar 1796	HANBURY,WORCESTER	Elizabeth Harris		
Mary Harriss	01 Apr 1796	BROMSGROVE,WORCESTER	Thos. Harriss, Eleanor		
Mary Harris	15 Sep 1796	BADSEY,WORCESTER	James Harris, Sarah		
Mary Harris	25 Jul 1796	WELLAND,WORCESTER	Wm Harris, Sarah		
Maria Harris	18 Jun 1797	Old Swinford, Worcester	Henry Harris, Elizabeth		
Maria Harris	02 Jun 1800	Pedmore, Worcester	John Harris, Elizabeth Harris		
Maria Harris	02 Jun 1800	HARTLEBURY,WORCESTER	John Harris, Elizabeth		
  

Death of Mary Harris 

Mary is in the 1841 census, (aged 43 or more likely 45), with William at Friar Street, but not in the 1851 Census.
The parish (not ecclesiastical) is St Nicholas, although one end of Friar Street is next to St Andrew’s.

Burials of Mary Harris in Droitwich parishes 1841-1851
Droitwich/Dodderhill Burials		Droitwich Registration
10 Sep 1842	Dodderhill												Age 8 (ANOTHER)
									1842-Q3 vol18 p184				
17 May 1843	St Andrew, Droitwich									Age 3 (ANOTHER)
24 Jun 1845	Dodderhill												maria Age 5 (ANOTHER)
1 Aug 1845	St Peter, Droitwich										
14 Sep 1845 Dodderhill												Age 42 Hill End (ANOTHER)
16 Sep 1845	Dodderhill				1845-Q3 vol 18 p174				Harrison Age 19 (ANOTHER)
18 Nov 1845	Dodderhill												Mary Anne Age 10 days (ANOTHER)
24 Dec 1845	Dodderhill												Maria Age 1 month (ANOTHER)
									1845-Q4 vol 18 p170				
									1845-Q4 vol 18 p172 (Mary Ann)
26 Jan 1846	St Andrew, Droitwich									Age 75 (ANOTHER)
									1846-Q1 vol  18 p182
									1847-Q2 vol 18 p217
11 Nov 1849	Dodderhill												Age 18 months (ANOTHER)

None of the above burials are correct.
The 14 September 1845 burial is from a transcript.  Need to check that the age is correct at 42 whereas 47 would be correct.

Mary Ann Carter Harris
29 Apr 1843	St Andrew, Droitwich	1843-Q2 vol18 p191