Honestly bizarre that tomatoes get all the flack for “not being a vegetable” because they're technically a fruit when:
A) There are a ton of fruits that get categorised as vegetables. Like this also applies to pumpkins, squashes and cucumbers.
B) The fucking mushrooms are standing there at the back of the crowd in this witch trial, trying to look inconspicuous because they somehow got into the vegetable club with no fucking controversy despite the fact that they're not even plants.
Vegetable is a cultural category, and total nonsense if you try to apply biology to it.
Things that come from plants are vegetables, except for fruits, grains, nuts, herbs, and miscellaneous. A fruit is, of course, any fruit that is not considered a vegetable. A grain is the fruit and/or seed of a grass, except when it's the seed of a non-grass. A nut is a seed from a tree, except when it isn't. Legumes are unknowable, and can be considered vegetables based upon vibes. Seeds from non-grass, non-legume, non-tree plants are unknowable or occasionally fruits.
That being said, I don't really understand on an instinctual level why mushrooms are considered vegan