Graphic Art - Not an Actual Scanned Image
(this is a speculative graphic, based on the written description only)

Obverse Design First line "JAMES STEWART & CO.". Second line "3230" (employee number). Last line "CANAL WORK".
Reverse Design Blank.
Metal Brass Size and Shape Round 39 mm in diameter, probably with some kind of hole or slot at the top.
Dates Issued Unknown. The Canal construction was from 1904 through 1914.
Issurer James Stewart & Company, who may have been an independent contractor working on the Panama Canal.
Numbers Issued Pieces in collector hands include #3230.
Rarity Very Rare. Manufacturer Unknown. Source Rulau's CZ 66. Slawsky Sept. 10, 1997 sale, lot 606.
Varieties None known.
Function Tentatively attributed as an employee id check for an independent contractor, working on the Panama Canal.
Note This piece is tentatively attributed to Panama Canal work as opposed to some other "canal work".
Population Count Known specimens are as follows:
  1. Check #3230 - Sold in the Slawsky Sept. 10, 1997 sale as lot 606 (simulated above).