The Chicago Board of Trade was the world's first futures and options exchange, trading various kinds of commodities (I think mostly agricultural, but I'm not sure). When it first opened in 1848, what commodities were traded there? Any data on commodities (particularly with volumes traded and/or prices) would be very useful.
This website: "The History of the Chicago Board of Trade" has a chronology based on what the Chicago Board of Trade traded with some statistics and descriptions. There is also this online reference to a 1917 text: "History of the Board of Trade" about the Board of Trade's early history.
It appears that the initial trade to go through the Board were "to arrive" or forward deliveries of flour, timothy seed, hay and corn. By 1859, a charter was established to standardise quality and product uniformity, as well as providing results from routine grain inspections.
Of course, there is the Wikipedia page with external links.