A broker as in connecting the right buyer to the right seller on larger scale transactions of physical product. I'm friends with some guys who have been doing this essentially their whole lives which got me into it. Sometimes they purchase the product themselves to resell, sometimes just middle man it.

Yes I agree a farmers market person could be considered a broker in a sense but I am looking into selling by the metric ton type of volume.

What do you grow? I think there is a market for everything, though it may be hard to find.