Like Merry in Lord of the Rings and Alice in Alice in Wonderland, to name a few, I am fond of mushrooms, even picking them in the field with my partner. Recently, I noticed that the word for these fungal growths is extremely different in each language, even among Indo-European ones. Therefore, I looked in the sources of its name, which were almost all, surprisingly, quite obscure.
The English word mushroom comes from old French meisseron. According to one article, located at http://www.fungi4schools.org/Reprints/Mycologist_articles/Post-16/Biodiversity/v03p088-090_word_mushroom.pdf, the root either means moss or, take a deep breath, mucus. This old French root sounds quite similar for the ancient Greek word for slime. Of course, it is impossible to prove; so you can choose that accept the more sympathetic connection between moss and mushrooms.
The French use the word champignon, which comes from the Latin campaniulis, field. Since some mushrooms are found in fields, that is quite logical. I am a bit confused why the Italian funghi, funguses, never transferred to French as in the much more modern espresso/expresso.
The Russian word call it гриб [grib]. According to one source, it appears to be derived from one of a few words describing a mound or hill, грести [gresti] or горб [gorb]. Again, the topographical feature, albeit different from the French, seems to be determining.
By contrast, the Hebrew word פטריות [petriot], mushroom, and its cousin תפטיר [taftir], mycelium or spores, appear in the Bible. It is a bit of a chicken and egg problem, but actually posed an issue for the matter of blessing. The decision was that mushrooms are not blessed like fruit and vegetables, not being sufficiently earthy. Another theory is the root of these words is פטר [ptor], which means break. The logic is that mushrooms break the earth. So, Hebrew takes a biological or agricultural approach.
The origin of the mushroom is like its nutritional value. It may be poor or obscure, but that doesn’t stop people to adding it to salads, sauces, or omelets, to name a few. Mushrooms are funghi to pick, prepare, and eat, wherever they come from.