Forest mushrooms not only have important functions within the forest ecosystem, picking the edible ones is a popular pastime for many people and an important commercial activity in many regions of the world. The formation of basidiomata is complex and has been the subject of legends and myths. One of these is the popular belief that mushroom harvests at full moon are particularly rich. Here we examine a total of 1715 dated mycological records, collected between 1990 and 2007 in five long-term observation plots in Switzerland to test for a possible relationship between lunar periodicity and mushroom yields. No such relationship was found, which means the claim that the moon phase influences mushroom production is based on myth.