I recall that Neil Shafer mentioned some of the literature on the topic of food stamp change. Perhaps some of the following would help Mr. Hopkins in his research.

Food Stamp Change Newsletter - published by Jerry Schimmel, San Francisco, from 1980 to 1984, 17 issues in all. Mailing list was small, a little >50, but included many well-known exonumia collectors and writers.

Food Stamp Change Token Stores by Jerry Schimmel, copyright 1980 - a 101 page nationwide and territorial listing of stores that are known to have issued food stamp tokens.

Iowa Food Stamp Tokens by Lewis K. Ferguson, April 1983 - 23 page well illustrated list published by Food Stamp Change Newsletter.

New York State Food Stamp Change Tokens by Gary Pipher, January 1982 -35 page partially illustrated catalog published by Food Stamp Change Newsletter.

New Jersey Food Stamp Tokens - 3 part catalog. Parts 1 and 2 by Gary Patterson, in Token and Medal Society Journal, December 1979, and supplement to Food Stamp Change Newsletter, October 1980. Part 3 by Al Zaika, manuscript awaiting publication in The Nor-Easter, newsletter of Northeast TAMS.

Food Stamp Tokens - 20 page fixed price list published circa 1980 (undated) by Paul A. Cunningham of Tecumseh, MI., an early advocate of food stamp change token collecting.

Neil Shafer's article(s) in The Numismatist

"Platco" Plastic Trade Checks - by David Gladfelter, in TAMS Journal, December 1977. This company made food stamp change tokens, among other exonumia products.

Plasco Plastic Specialty Tokens - by David Gladfelter, TAMS Journal, December 1978. The company was a large producer of food stamp change tokens.

These sources should be available from the ANA library and/or the TAMS library.

To read the earlier E-Sylum articles, see:
FOOD STAMP CHANGE TOKEN INFORMATION SOUGHT (www.coinbooks.org/esylum_v18n04a06.html)
THE HISTORY OF FOOD STAMP CHANGE TOKENS (www.coinbooks.org/esylum_v18n05a11.html)
FOOD STAMP CHANGE TOKEN RESEARCH UPDATE (www.coinbooks.org/esylum_v18n06a11.html)