From A Wiki in the Desert
In T9, there is an about 5000:1 chance of finding a Wild Pepper Plant. When you click on it you will be able to harvest a Pepper Seed.
As far as we know, Cheill was the first player to actually find a Wild Pepper Plant and receive a seed from it.
It apparently looks exactly like a Regular Pepper Plant:.
Some information was told to Fairy by Malard, who later unintentionally posted a screenshot of that chat while teasing Sheeple by not allowing him to pick up onions anymore.
Pepper Seed yield data