Because HeatherJulie has honed in on the Richard christening, I wanted to post the other so you didn't think there was only the one:
Name James Pollard Stephens
Gender Male
Christening Date 23 May 1798
Christening Place REDRUTH,CORNWALL,ENGLAND
Father's Name Wm Stephens
Mother's Name Mary
He may have dropped the "Pollard" later on (I have some christened with middle names who lost them after a while). Of the two, this one would be my first focus because of his naming his first son William (and of five sons, did not name one Richard).
Other children that appear when you put in William and Mary as parents (in Redruth specifically) include:
Ann ch. 5 May 1782
Mary ch. 2 Jun 1782
Mary ch. 23 Apr 1783
Thomas ch. 25 Jul 1784
John ch. 17 Jul 1785
Ann ch. 21 May 1786
[James 1798]
John ch. 17 Jan 1790
William ch. 19 Mar 1792
Ann ch. 10 Aug 1794 (bd 28 Jul 1795?)
Ann ch. 23 Oct 1796
Christian ch. 8 Sept 1799 (bd 23 Dec 1799?)
Christian ch. 23 Nov 1800 (may also die later)
George Pollard ch. 27 Oct 1802
(found on FamilySearch- burials C-OPC)
I can't confirm at this point that all of the above children are from the SAME William and Mary, but on the potential that this is one family... Thomas, John and George obviously appear in his children, which also lends to this being a priority. Of course I haven't looked into Elizabeth's family though, so I don't know whether she had relatives of those same names. Since five out of five names of his children come from this side, I'd focus on this personally.
~ added, marriage of William STEPHENS to Mary POLLARD 15th Sept 1781 St Uny, Redruth (Cornwall OPC)