Photo and ephemera collector Jim Linderman suggests--or jokes, I can't tell--that the 1927 promotiocational classic, Heinz Kindergarten Book: Pictures To Trace might have provided early source material for Andy Warhol.
Who knows? Warhol was certainly a voracious a collector and appropriator of advertising and popular imagery.
In 2003-4, the Huntington Library in San Marino exhibited a huge collection of art educational materials donated by Diana Korzenik, which included the Heinz Kindergarten Books and other vintage marketing/coloring books. "Drawn to Art: Art Education and the American Experience, 1800-1950" isn't documented online very well, but the 1,400-piece collection is apparently available for research.
UPDATE: In addition to his entirely plausible explanation for suggesting a Warhol/Heinz Coloring Book connection in the comments below, Jim has expanded on what he meant--and posted more sweet Heinz scans--on DTDB.
Where Warhol Got The Heinz? [dulltooldimbulb]
"Drawn to Art: Art Education and the American Experience, 1800-1950" [absolutearts.com]
A Brief History of the Korzenik Collection of Art Education Books and Ephemera, Accessible through RLG Cultural Materials [worldcat.org]
Heinz Booklet 1927 Pittsburg PA.
Andy Warhol BORN 1928 Pittsburg PA. So Quite possible! It's one for the art historians.
Readers may also like my other art sites, index at
http://www.dulltooldimbulb.com
Thanks!