Various secondary sources call him James William or James Wilson, but I have yet to find a primary source calling him anything other than James.

— born in Fayette Co., VA [now WV]:
2.  Levi SIAS, b. Jun 1835; m. Sallie R.HILL
3.  Isaac SIAS, b. 1837/8
4.  James W. SIAS, b. Sep 1835-40 {1850: 10, VA; 1860: 22, VA; 1870: 32, VA; 1880: 44, WV} 

— born in Mercer Co., VA [now WV]:
5.  Andrew Lewis SIAS, b. 28 May 1840; m. 1867, Lincoln Co., WV, Martha Ellen LAMBERT
6.  Noah SIAS, b. Jul 1842; m. Rebecca __?__
7.  Charlottte F. SIAS, b. 6 Feb 1844; d. 1917; m. Washington PLUMLEY  (1840-1910); both buried Plumley Cemetery, Big Laurel, Sias, Lincoln Co., WV
8.  Henry C. SIAS, b. 1846/7; m. Sarah PLUMLEY
9.  John Sullivan SIAS, b. Dec 1849 

1.  Marriage Record:

2a.  Census Index:  U.S. Selected Counties, 1830 (Broderbund CD-315):

1830

Sias, James

VA [now WV]

Monroe Co.

p. 37

He is the only SIAS in the state, and he may be our subject's father.

2b.  1830 Census Index and Digital Images (online at Ancestry.com):  the images for Monroe Co., (W)VA, are missing, at least as of 13 Jul 2002.

3a.  Census Index:  U.S. Selected Counties, 1840 (Broderbund CD-316):

1840

Sias, James

VA [now WV]

Marshall Co.

Mercer

p. 258

This record is mis-indexed (see next source).  The only other SIASes in the state are Frances and Rachel in Wheeling, Ohio Co., (W)VA.

3b.  1840 Census Index and Digital Images (online at Ancestry.com; Image #19-20 of 21; extracted by Diana Gale Matthiesen):

1840

VA [now WV]

Mercer Co.

pp. 257B-258A

Sias James

400 010 - 010 001

0100000

no slaves

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
4 males	4 or under	1835-1840	= Andrew (b. 1840) = James (b. 1838) = Isaac (b. 1837/8) = Levi (b. 1835)
1 male	20-29	1810-1820	= James (b. 1811/2)
1 female	5-9	1830-1835	= Eliza (b. 1833/4)
1 female	30-39	1800-1810	= Rebecca (b. 1805/6)
1	person engaged in agriculture

The list is roughly alphabetized, so no neighborhood reconstruction is possible.

4.  1850 Census Index/Microfilm (online at GenealogyLibrary.com):  42nd District, Mercer Co., VA [now WV], p. 162B, 196/196, enumerated 6 Aug 1850 (extracted by Diana Gale Matthiesen):

James Sias Est	38	m	Farmer		Va
Rebecca "  Est	40	f			"
Eliza   "	16	f			"
Levi    "	14	m			"
Isaac   "	12	m			"
James   "	10	m			"
Lewis   "	9	m			"
Noah     "	7	m			"
Charlotte "	5	f			"
Henry     "	3	m			"
John      "	8/12	m			"

He is the only SIAS in the state.

4a.  Census Index:  U.S. Selected Counties, 1860 (Broderbund CD-318):

1860	Sias, James	VA [now WV]	Boone Co.	Ballardsville P.O.	p. 114
1860	Sias, James W.	VA [now WV]	Boone Co.	Ballardsville P.O.	p. 114

James W. is not married, so there's no earthly reason for him to have been indexed.

4b.  1860 Census Images (online at Ancestry.com; Image #114-115 of 118):  Ballardsville P.O., Boone Co., VA [now WV], pp. 114-115, PN 114-115, 729/729, enumerated 27 Jul 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

James Sias	48	M		Farmer			Monroe Co Va
Rebecca "	54	F					Greenbrier Co Va
Evy      "	25	M		Farm Labour			Fayette Co Va
James W   "	22	M		Farm Labour			"
Andrew S/L "	20	M					Mercer Co Va
Noah Sias	18	M					"
[next page]
Charlotte F Sias	16	F					Mercer Co Va
Henry C      "	13	M					"
John M       "	10	M					"
Cynthia Adkins	11	F					Raligh Va

The senior James's birthplace was first entered as "Greenbrier," then scratched out and replaced with "Monroe."  There are many ADKINS in the neighborhood, plus one PLUMLEY.

5.  AIS (Accelerated Index System) 1870 Census Index (online at Ancestry.com):  can't find.

6a.  Lincoln County, West Virginia - 1880 (online in the WVGenWeb Archives):  Lincoln Co., WV, E.D. 69, p. 210, Reel 1406, enumerated 11 Jun 1880 (extracted by Al Zopp):

SIAS, JAMES	W	M	68	Head	M	Virginia	Virginia	North Carolina
SIAS, REBECCA	W	F	72	Wife	M	Virginia	Virginia	North Carolina

6b.  1880 United States Census and National Index (LDS Family History Resource File: CD-ROM Library):

Census Place: Union, Lincoln, West Virginia
Source: FHL Film 1255406; NARA Film T9-1406; Pg 210C
	Relation	Sex	Marr	Race	Age	Birthplace	Occupation	Fa	Mo
James SIAS	Self	M	M	W	68	VA	Farmer	VA	VA
Rebecca SIAS	Wife	F	M	W	72	VA		VA	VA

7.  Anon.  1970. "Queries." Maryland Genealogical Society Bulletin 11(3): 108.

SIAS, James b Monroe Co., Va. 1812 m Rebecca ? b Greenbrier Co., Va. 1810 Need parents of both. Liv Mercer, Boone Co., VA. 1840/50-1860, Lincoln Co., W. Va. 1880. Ch: Eliza; Evi; James; Isaac; Andrew Lewis; Noah; Charlette m Washington Plumley; Henry m Sarah Plumley; John m Martha Jane Stowers. Isaac went west where?

8.  LDS.  Family Search: Internet Genealogy Service: Ancestral File.  The AF shows all the children born in Greenbrier Co., WV, but the census does not support that location.

9.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).

10.  Descendants of John Sias Sr. by Garey L. Marshall.  Has James married to both Rebecca ADKINS and Mary Ann HUGABOOM, which cannot be (see below).

11.  Broderbund.  World Family Trees.  Vol. 2, Pedigree #4652; Vol. 34, Pedigree #1581.

12.  Broderbund.  World Family Trees.  Vol. 28, Pedigree #1767.  Says James William SYAS, s/o James & Patience SIAS,  married Mary Ann HUGABOOM and fathered George Harriman SYAS, born 5 Oct 1857, Kalamazoo, MI.  James was married to Rebecca in the 1850 and 1880 censuses of VA/WV, so it's impossible for him to have been married to Mary Ann HUGABOOM in 1857, nor is there any evidence that our subject was ever in Michigan.  Yet this record may be correct.  That is, that there was a James William SYAS who was s/o James & Patience (DWIER) SIAS and he is the one who married Mary Ann HUGABOOM, while the James SIAS who married Rebecca ADKINS is not the son of James & Patience, as several other lines of evidence also indicate.