Still looking for any digitized ones, but it looks like the majority of them I've found so far are held in university or museum archives (Washington State and Oregon State both have several, apparently) and they haven't digitized the contents yet.
Did fine one from the VERY start of the 20th century (1901) which occasionally provides the info you're looking for, if you're interested, but for the most part avoids providing that info unless that particular seed variety was getting a full write-up as a new or featured item.
Something potentially promising: Found a digitized copy of The American Gardener's Calendar from 1806 which mentions "Indian Corn" (appears to be referring to Flint Corn) on pg. 362.
It's been a solid while since I did any work related to archives (and even that wasn't a lot, it was an internship for my undergrad). I'd be happy to do what I can, but could you be more specific what it is you'd need?
I found some RH Shumway catalogs on Internet Archive. From what I can tell, it just says they are all "early" to mature, but no time frame given. But there's lots of other catalogs archived, they might be more specific https://archive.org/details/rhshumwaysannual1892rhsh/page/11/mode/1up
Comments
https://www.biodiversitylibrary.org/page/20142799#page/3/mode/1up
The Catalogue of G. Thorburn & Sons of 1832
https://archive.org/details/rhshumwaysannual1892rhsh/page/11/mode/1up