Keville Family — Town of Moyne, Civil Parish of Shrule,* County Mayo, Ireland
Thomas Keville (M. Bridget Carr)  [2 & per Kevin Geraghty email]
... James Keville (bp** 17 Jun 1832 ; m. Biddy Ryan)
... Patrick Keville (m. Mary Spellman)
From the Griffith's Valuation , about 1855:
At this time, the English survey found 52 parcels of land in the town of Moyne (within the civil parish of Shrule, County Mayo) — 880 acres of "rateble land." Most of the land was owned by Joseph Burke.
James and Patrick Keville operated two parcels (#3-27 acres; #4-29 acres), owned by Paul Ward and Joseph Burke. James is given the letter a, which means he's the "farmer" so I assume it means he is the older brother.
Their buildings were valued at less than £2 on each parcel, which probably meant they were the usual earthen structures with thatched roofs. They, in turn, rented out a cottage to Patrick Doherty, probably a laborer or "cottager" who helped them farm and had his own little patch of potatoes.
At the time of the 1901 census, (the same?) two parcels were operated by Bridget Keville and James Keville. Which Bridget and which James is the question... maybe irrelevant, probably one from the "James" line and one from the "Patrick" line.
A marker between the two large Keville tombstones at Moyne says: "KEVILLE TONROE." Tonroe is in the civil parish of Kilkilvery, south of Shrule in County Galway, but there must have been a strong family connection to have put up what looks like a cross-reference to Tonroe.
Griffith's Valuation from the 1850s, page 42, lists James Kevill renting 62 acres of land from Arthur Guinness. Also in Tonroe is William Carr, who might be related to Bridget Carr, who married Thomas Keville (Maggie Keville's grandparents, above).
The 1901 Census  lists Julia Keville, age 70, as the head of household, with the occupation of farmer. This may be Julia Lynskey Keville (see below). She is living with Thomas Keville, age 27.
Some people have found this page searching for a Keville connected to a Lynskey. Maggie had a cousin Julia Keville, who lived in Chicago about the same time as Maggie. Julia's parents were Michael Keville and Julia Lynskey (see Tonroe Connection above). Several members of that branch of the family moved to New Zealand. 
*Shrule is in County Mayo near the Galway line.
**bp = baptism
 Shrule (Moyne) Baptism [bp] records, from Shrule.com. These give child's name and parents (including mother's maiden name). Thomas and Bridget were listed as the parents of James.
 Tithe Applotment (1823-1838) — used for calculating how much was owed to the Church of Ireland.
 NOT listed in Shrule baptism records
 Moyne (Shrule parish) cemetery
 Kathleen Price research
 Poor Law Union of Ballinarobe, p. 162, 1854-56.
 from Shrule.com.
 Rose Park research