Preservation varies by mushroom type. These are Chanterelle mushrooms and the most common system is to quick-freeze them individually (on cookie sheets, for example) before bagging them. The usual recommendation is to dry-clean them first rather than washing them, and they hold up quite well.
We probably could make a killing selling them, they tend to be quite pricey as well. Mainly though we're looking for some healthy tasty foods for ourselves and this is obviously cheaper than buying them.