One of the benefits of being half-Caitian is non-human species tend to be more... open with you about what they think about humanity and its foibles.
So to celebrate first contact day, let me tell you why mushrooms persuaded the Vulcans to invite humans into the Federation. /1
So one thing I don't think humans realise is just how weird most other species think their food choices are.
Because on most planets or stations humans live on, and most ships they'll ever travel on, Star Fleet included, "default to human" is standard 🙄 /2
Indeed they're so busy laughing at other species food choices that they fail to spot the absolute BAFFLEMENT those species have towards one particularly bizarre element of human food:
Mushrooms. 
/3
On almost literally every planet in the galaxy where mushrooms (or their nearest fungal equivalent) are present, one of two things is true about mushrooms. Sometimes both:
1) They are almost all massively poisonous.
2) They are sentient.
THIS INCLUDES EARTH, where 1) is absolutely true. /4
I can't tell you how strong this instinct is. Some species can't even be in a room where they can SMELL mushrooms being cooked.
I can JUST ABOUT manage it. Because I'm half-human. But it still gives me a massive case of the fears and I can't eat them. Makes me hurl. /6
What that first contact ship reported back, with almost wide-eyed astonishment, was:
1) The sheer cavalier approach to warp tech that somehow worked
2) THAT THEY SERVED MUSHROOMS IN FOOD IN THE BAR
And it recommended humanity get fast-tracked for an alliance, despite the risks. /7
In the planetary archives on Vulcan, you can access this report. It's an INCREDIBLE read. If you're on planet, just do it. You only need to apply for a temporary reader card. You won't regret it.
It argues that humanity is the 'MEF Collision' the Vulcans have been looking for.
Today, we know that humanity is the "Designated Exploration Species" of the Federation. That's why Star Fleet is so heavily human. 'MEF Collision' is the original Vulcan term for the species they were trying to find for that role.
It stands for:
"Mates, Eats, Fights" /8
Vulcans are smart. Smart enough to know they are TERRIBLE explorers. They wanted a MEF Collision to uplift. A species which, on seeing a new thing, thinks:
"Can I mate with it? Can I eat it? Should I fight it?"
Mushroom soup proved to Vulcans that humanity was a candidate. /9
To be crude, Vulcan High Command knew that for their growing hope of a galactic federation to prosper, they needed a species that had aligning ideals BUT ALSO was utterly committed to fucking around even if that often meant finding out.
And they gambled on humanity being the one.
And BOY HOWDY did humanity deliver.
Since day dot humans have been the fuck around merchants of the Federation, backed up by Vulcan science and diplomacy.
The love between humans and vulcans, as a species, is genuine and deep. They are the shared rock of the Federation. /10
And it all started with mushrooms. With the command crew of the T'Plana-Hath sitting there, that April evening, and watching in awe as humans casually nom nommed mushrooms. In soup. On burgers. With bacon. In so many different ways.
And they thought:
"This species fucks around. And accepts that sometimes they'll find out." /11
Because somehow humans had evolved to eat mushrooms. No other race they'd encountered in the galaxy, including Vulcans, could do this.
The Vulcans even discreetly tried to feed the bar cat some mushrooms to see if it was a planet thing. Nope. Cat refused.
They were in awe. /12
Of course in the century since, it's all become glossed up in stories of shared ideals and fancy language about explorer species and exchange of ideas.
But they still teach the mushroom thing in Vulcan schools. They're just too nice to mention it in front of humans. /13
But if you go to Vulcan, to that planetary archive, you can read that original report.
You can see the joy, fear, hope and awe in the words of the commander of the T'Plana-Hath, even through his logic. You can see the representative of one species realise he has discovered another that can perfectly compliment his own.
It is a moment of beauty and history. A moment that sums up EVERYTHING the Federation is about: that when we work together, we become our best selves.
And it's because of mushrooms.
Happy first contact day, everyone. 
/END
@catboy_cdr I look after an idiot spaniel, and he will try to eat anything - he's not very into mating or fighting, but he is very food-oriented.
And not even he will touch a mushroom.
The only other thing he point blank refuses to acknowledge as food (and bear in mind we're talking about a creature who gnaws firewood into splinters for fun here) is soy based yoghurt. Perhaps you should should try some of that on the Vulcans?
Lt Cdr. Bull, Shuttle Chief
🍸Pooka🥕Boo🍸
Ben Curthoys