After receiving your question, the Dear Rich Staff immediately went to the refrigerator and looked at the two ears of corn recently purchased from the Other Avenues food coop and yes, actually they did contain trademarks -- two to be exact. The small sticker contained the name of the farm from which the corn originated and a certification mark that authenticated the corn's organic-ness. Ditto for the tomatoes, the kiwis, and the apples. The green beans and mushrooms did not have trademarks on them, although I am informed and believe that the bin from which they were selected at the coop did have the name of the farm from which they originated.
We do not have any cord wood to examine because being from northern California, we avoid using our fireplace for obvious reasons. However, we used to have a wood stove when we lived in Indiana. We never bought cord wood at at the local Ralph's-T-Mart or Wright's IGA because it was cheaper to buy it from a local who drove it over in a pick up truck emblazoned with "Frank's Firewood," a trademark that permitted us to distinguish Frank from other suppliers. (You are correct, however, that each piece of wood was not marked with a logo -- unlike the engineered wood we buy from Home Depot.)
Should We Qualify Our Statement?
We suppose we could qualify our statement to say, "Almost all products contain trademarks in some form." But why bother? To qualify the statement implies that we are in denial as to the tsunami of marketing that has pulled us deeper and deeper into the sea of consumption -- all of it inherently dependent on the illusionary power of trademarks. Trademarks allow us to justify our purchases, and that allows us to justify the work we had to do to make that purchase. As our trademark mentor once wrote, "No busy working person in a developed society has hours to spend agonizing anew over every single purchase at the supermarket or elsewhere. Everyone is too busy trying to earn the money to be able to make purchases in the first place."