Buddyb, for button collectors and diggers, button-ID is divided into two basic categories: Military buttons and Civilian buttons.
The two most-extensive books on American Military buttons:
"Record of American Uniform and Historical Buttons: Bicentennial Edition" (with Supplement) by Alphaeus H. Albert. 511 pages. It covers US (and Confederate) militray buttons from 1776 through 1976. Cost is about $39 to $45.
"Uniform Buttons of the United States 1776-1865" by Warren K. Tice. 519 pages. Published in 1997, which is 21 years after the final version of the Albert book, Mr. Tice's book therefore contains two decades of additional research and information, including many specimens which do not appear in the Albert book. Cost is about $60 to $70.
A number of much-smaller books have been published which show and identify various types of Civilian buttons, from various eras of history. I do not own any of those, so I rely on a very educational internet website: the United Kingdom Detectors Finds database. Its section on buttons is fairly extensive.
http://www.ukdfd.co.uk/
As indicated by BigCypressHunter's previous reply in this discussion-thread, the website of the Waterbury Button Company is very useful for both Military and Civilian button-identification.
www.waterburybutton.com
For dating a button by the Maker's-Mark on its back (commonly called a "backmark"), the very best book is "American Military Button Makers and Dealers; Their Backmarks & Dates" by William F. McGuinn and Bruce S. Bazelon. 189 pages. Despite the title, it actually also covers makers & dealers of Civilian buttons. It's especially useful for its photo-pages showing subtle changes in the backmarks of major button-manufacturers who were in business for many decades, or even more than a century, such as the Scovill Manufacturing Company/Waterbury Button Company. Cost is about $25 to $29.
