My gut sense tells me that mushrooms don’t really fit in well in the 4 food groups, but looking at the (newly designed) food pyramid, it seems that the “vegetables” category is the best place for them. However, something is keeping me from accepting that completely and without reservations. Are mushrooms really considered vegetables? If not, what are they, and what food group do they share the most in common with nutritionally? What’s their nutritional value anyway?
The government considers them “other vegetables,” and equates them serving to serving with all others. Mushrooms are a great source of goodness. 
From here:
NUTRITION OF THE WHITE MUSHROOM
FOOD VALUE per 100g
Energy 13 kcals (55kJ)
Protein 1.8g
Carbohydrate 0.4g
(of which sugars) 0.2g
(starch) 0.2g
Fat 0.5g
(of which saturates) 0.1g
Fibre 2.3g
Sodium 5.0mg
I know some vegetarians consider them a protein-rich food, thus lumping them in with the meats, but non-vegs can probably count them as a vegetable.
Biologically/taxonomically, fungi are a kingdom of life separate from both the plant and animal kingdoms. But in the nutritional sense, they’re vegetables.
–Cliffy
They don’t belong to either the plant or animal kingdoms, but since the context of the term vegetable here is probably the culinary one, they’re vegetables - because they grow in the soil, they don’t run away from you when you approach them and they don’t shriek when you slice them.
I’d been wondering the same thing myself. Nice to know (from silenus’s source) that they have several minerals and b vitamins, too. I don’t see any mention of the normal “green and leafy” or yellow vegetable vitamins, though, so I guess we still need to eat our green beans and squash.
Note that that’s a 100g serving, which is like 4 ounces. Not an enormous amount, but still quite a bit. And you don’t get much in exchange. Don’t give up the broccoli just yet.
I thought mushrooms would be closer to fruit, since they are the fruiting body of a fungus.
Similar to a lemon being a fruiting body of a lemon tree and an egg being the fruiting body of a chicken… are eggs chicken fruit? mmm I suppose not, since they dont grow in the soil (application of the Mangetout premise).
Are carrots and potatoes vegetables too? They are actually roots, right? Are onions vegetables too? Onions are roots too, right?
I think we should just call them plants or something. Wait, a mushroom isn’t a plant though.
I love avacados. Are they fruits?
A vegetable refers to any plant or part of a plant. Why shouldn’t roots count? We accept stalks, leaves, shoots, and just about anything else as vegetables. Roots certainly are as well. Fruits, under this (biological) definition, are a subset of vegetables. Mushrooms, however, still are not, as they just plain aren’t plants.
Fruit refers to fleshy material surrounding a seed. So an avocado is definitely a fruit, as is a tomato, a green bean, a squash, or a pepper. Of course, all of those things are used in cooking (at least in this culture) as vegetables, and not fruits, and under that idea of customary uses, mushrooms are a vegetable as well.
Is it me or does the new pyramid look even more ridiculous than the last?
I might be unique, and I’ve never really discussed this with my doctor, but it seems that for me grains or cooked starchy veggies = almost instant gastric upset. I like to eat them, but I pretty much have to treat breads, cereals, pastas, rice as if they were ice cream cake(i.e. a tasty treat you get once in a while) and generally have to subsist on raw vegetables, fruit, dairy and meat. Mushrooms never cause problems though, so to me, mushrooms are a “green” vegetable like broccoli (even though they aren’t actually green).
You may be slightly celiac. It’d be worth your while getting it checked out.
If a mushroom isn’t a plant, then what is it?
a fungii
they probably would be considered a vegitable though they are a fungus. 
Like I said before, botanically, they are not, since they are fungus. A fungus is not a plant. Culinarily, they are usually regarded as vegetables.
I always thought that the living world could be safely divided into flora and fauna. Is that not true?
Nope. Fauna, flora and mycota :).
Actually people frequently speak of “mycological floras” but the above term is the correct one. And as is pointed out above there are actually mutiple kingdoms beyond that ( I was taught a standard five, with debate up to 20-odd ).
- Tamerlane
I think when my dad was in elementary school they still taught the two kingdom model - was your basic biology education a long while back? Now the standard model is five kingdoms - animals, plants, fungi, protista (protozoa), and monera (bacteria). One system proposes a superclassification into two empires: eukaryotes (lifeforms with nucleated cells) and prokaryotes (no nuclei - that is, bacteria), and a more recent one uses three domains: eubacteria (true bacteria), archaebacteria, and eukaryotes.
Wikipedia link: Kingdom
I’m unable to find it now, but if I recall correctly there was a similar thread a couple of years ago where Colibri stated that mushrooms are more closely related to humans than they are to green plants.