David Thompson and I have begun to work with a listing of members of the Chicago Board of Trade (CBOT) from the 1898 tax period that can be found in an annual volume called: "Annual Report of the Trade and Commerce of the City of Chicago." These were published for generations, and can be found for the years 1898-1902 and beyond, even as ebooks through Google and downloadable as free .pdfs.
Futures contracts required tax stamps, though the level of taxation didn't require the use of dollar values on most contracts. Battleships predominate, and a large number of the battleship stamps that can be found in collections were cancelled by CBOT members. Today is the first example, cancelled by the firm Charles E. Gifford & Company.
C. E. G. & Co.
NOV 11 1899
In 1900, the listed members of the CBOT from the Charles E. Gifford firm include:
#2054 Charles E. Gifford
#5252 Charles E. Gifford Jr.
#2524 Isaac Gifford