There's a place in Amethyst where there are listings, but I doubt its comprehensive. Its also uncategorized, so it would be hard to find market data on specific things.

Mushrooms are a great idea, especially if you get a deal with a restaurant for regular supply. It would be great to see more stuff like that denominated in sats. I think this is probably where meetups really could shine - connecting bitcoiner farmers with bitcoiner restaurants or similar.