More bits of data, mostly relating to the Ivey family. Some of this is rather depressing, as both the Lott and Ivey families seem to have led rough lives with numerous instances of infants, children, and relatively young adults dieing. It is perhaps unsurprising that family members would not have wanted to talk much about this history.
I couldn't find a direct link between Mamie Lucille Ivey and the people I think are her parents. The birth does not appear to be available online. You might or might not be able to find such a record either on microfilm at a Family History Center or by direct request from the State of Texas.
From what I've seen of the published records, there is a gap between 1909 and 1926 where birth records are not available, and your search unfortunately falls right into that gap. Another option would be to search for an obituary for her or a known sibling and perhaps find the parents there.
Found this on the texas genweb sitehttp://www.lamarcountytx.org/
Lott, Nancy Jane 183005
Birth: 04/29/1871 Death: 07/17/1958 Marriage:
Cemetery: Evergreen (37-52-03)
No image Update info
Notes THE PARIS NEWS, 18 Jul 1958. 'Mrs. Nancy Jane Lott, 87, longtime resident of Rattan community, died Thursday in a Quitman convalescent home. She was born in Alabama, April 29, 1871. The funeral, in Paris, will be held Saturday at 10 a.m. at West Paris Church of Christ by Hubert Roach. Delta Funeral Home of Cooper to make burial in Evergreen Cemetery, Paris. These children survive: John Lott, Anson; Harrison Lott, Dallas; Jess Lott, in Missouri; Melvin Lott and Mrs. J.M. Partridge, Paris, and Mrs. Rosa Wilson, Cedar Hill; 18 grandchildren, and a sister, Mrs. Susie Mitchell, Howland.'
Buried next to W. Alyne Bosarge.
(Son Melvin's obit is there as well.)
The Delta County TxGenWeb site has marriage entries for
Samuel Ivy + Mary Green; 9 Apr 1899
Willie Ivey + Laura Mayfield; 6 Dec 1925
J. J. Lott + Mattie Smart; 2 Feb 1919
Tom Lott + Ocie Adams; 28 Aug 1919
W. H. Lott + Velma Horton; 25 Mar 1916
(Apparently first wife of W.H. Sr. was Horton, not Parton. She shows up in 1910 Delta census as a niece of Clifton Glover. In 1900, she's listed as Alma Horton, granddaughter living with James and Martha Glover in Lamar. The Glover family is from Arkansas -- perhaps your family stories are tied to them?)
There are a Sam Ivey Sr. and Jr. recorded in 1900 Delta County. They are listed as black, so probably not your family, though possibly a source of confusion when looking through index listings.
TxGenWeb Fannin has...
W.G. Ivey and Willie Ivey buried New Harmony Cemetery. They look about the right ages to possibly be father and sister of Mamie Lucille.
Three burials are marked as children of W.G. and S.E. Ivey, two infants, one age 4. This family had a hard life.
Texas County Marriage Index at www.familysearch.org
W. G. Ivey + S. E. Dunkins; 21 Oct 1897; Fannin
WWI Draft Registration
Sam Ivey; Ladonia; born 2 Oct 1898; father W. G. Ivey
Eldest son of W.G. and Emmer appears to have been James Sam Ivey. This is looking very much like the family of Mamie Lucille.
1910 census shows both W.G. Ivey and Emmer S. born Tennessee.
Familysearch Texas Deaths lists an Ella Ivey born 1 Jun 1876, died 13 Jul 1912 near Ladonia. Parents James Duncan and Elizabeth Talant in Tennessee.
Ella was married to Robert W. "Bob" Ivey. I would guess that William G. and Robert W. are closely related and that Emmer and Ella might have been sisters or cousins, but I can't find the links.