I was listening to a podcast hosted by a Vegan and he made the comment “Well this kind of stuff is my bread and butter. Of course since I’m vegan it would be my vegan bread and my vegan butter”.
Is bread not vegan?
Some bread has milk, eggs, or butter, so not vegan.
They could have also just been doing a bit of wordplay.
Also, a vegan might object to the use of yeast.
Well, technically yeasts are a member of the fungus family.
nm___
Vegans don’t eat mushrooms?
Wait. Somebody help me escape some bona-fide ignorance here. Butter is vegan?
Vegan “butter”.
Yeast is considered vegan by every vegan I’ve ever heard from on the subject. Honey, however, is not, and is often found in bread. Also, many bread products contain L-cysteine, a preservative usually made from feathers, so that’s obviously not vegan either.
AFAIK, yes, mushrooms are vegan.
Despite the fact that they are more closely related to animals than to plants?
Some vegans are not rational. I mean carrots have many nematodes. But bees are slaves? 
Speaking as someone who bakes most of the bread I eat:
Bread can be vegan, but often isn’t. The addition of egg, milk, honey, or various other potentially objectionable things are very common in commercial bread, and in quite a few home recipes.
This isn’t something the average non-vegan non-baker is aware of.
A vegan would have to do a lot of label-reading before buying commercially made bread, unless the bread is labelled “vegan”.
They lack even a rudimentary nervous system, however. Thus the argument about pain and suffering wouldn’t apply.
“But yeast is alive! Vegans can’t eat it!” - a comment I get a lot on reviews of vegan foods. Yeast is alive, like every fruit and vegetable, nut, seed and bean.
The criterion for veganism is not ‘was it ever alive’.
Yeasts, mushrooms, or vegans?
No. But you can get vegan “butter” that is basically margarine.
It’s got nothing to do with slavery. Vegans do not eat any animal product and honey is an animal product.
Just to add to the confusion: wine is mostly non vegan, nor is champagne (though there are vegan wines and champagnes):
The majority of people are unaware that wine, although made from grapes, may have been made using animal-derived products. During the winemaking process, the liquid is filtered through substances called “fining agents.” This process is used to remove protein, yeast, cloudiness, “off” flavors and colorings, and other organic particles. Popular animal-derived fining agents used in the production of wine include blood and bone marrow, casein (milk protein), chitin (fiber from crustacean shells), egg albumen (derived from egg whites), fish oil, gelatin (protein from boiling animal parts), and isinglass (gelatin from fish bladder membranes).
In the end I am afraid that determining whether something is vegan or not is as arcane a science as determining whether something respects religious precepts or not: it can look absurd to those who are not members of the religion in question. I have the feeling that more or less strict vegetarianism is rational and understandable, even to an outsider who does not practise it, but veganism can feel like an arbitrary religion to the excluded outsider.
So are many plants. They need bees to pollinate.