I’m making this a separate post from berries or mushrooms, since a number of types of foods could be packaged in these baskets.
I have reacted to both berries and mushrooms in containers like this, and there are a number of reports on the Facebook corn allergy group of others reacting to foods packaged in these containers. It is possible that it isn’t the containers but rather the food itself, but I avoid them just in case.
I don’t know what is in them that is so corny. They are supposed to just be “molded fiber” from wood pulp. I guess they must put starches in or something to make them more absorbent of berry juice? Maybe the dye that makes them green? The main manufacturer is a company called Pactiv and the material is specifically called Berigard. I can’t really find information on what these baskets are made from other than “pulp fiber” and why they would be more of a problem than, say, egg cartons, but they really do seem to be an issue for myself and many others.