Charles A. Siringo published a version virtually identical to Lomax's in The Song Companion of A Lone Star Cowboy in 1919. Since most of the other songs also appear virtually identical to those Lomax published in the 1918 edition of Cowboy Songs and Other Frontier Ballads, I must conclude that either Siringo took the texts from Lomax (just as Lomax stole many songs without acknowledgement or credit from Thorp and Clark) or that Siringo was Lomax's source for these songs, even if Lomax published them first.

In the last verse of "The Dying Cowboy", where Lomax has (convulsive) "shadow", Siringo has "shudder". The latter makes better sense to me.


For what it's worth, these are the songs in Siringo's book:
The Lone Star (credited to Mrs. Lee C. Harby)
The Dying Cowboy (= O Bury Me Not)
Texas Rangers
Mustang Gray
Cow Boy Carol (= Cowboy's Soliloquy, by McCandless; Lomax: "The Cowboy"; credited here to Wm. Thompson and C. C. Clark)
Sam Bass
The Buffalo Hunters
The Tough Longhorn
The Dying Ranger
The Cowboy's Christmas Ball (by Larry Chittenden, but uncredited here)
A Home on the Range (by Brewster Higley, but uncredited here)
The Gol-Darned Wheel
A Jolly Cowboy
The Eastern Shores of the Rio Grande

The only songs which do not appear in Lomax's 1918 edition of Cowboy Songs and Other Frontier Ballads (per the scan at the Traditional Music Library site) are "The Lone Star", "The Tough Longhorn" and "The Eastern Shores of the Rio Grande".