We think we have found what could be the worlds largest morel mushroom growing outside of Witt Illinois. It is at KO produce on 15th avenue just outside of Witt Illinois where you can buy local home grown fresh produce every Saturday from 7am to 1pm. Walt and Dawn King the owners of the property also service many local stores and restaurants. keeping them stocked up on fresh veggies. Check out some of the pictures below of a few things they have to offer. About the mushroom.