For Knott, preserving native genetics is a critical mission. "They've got seed banks for plants. But it didn't look like anyone was doing it for mushrooms. I want to be that guy."

Back in the muddy field in Sussex, my mushroom-cloning experiment is one small part of the answer to this. The grey oyster mushroom I have in front of me is itself a clone of a native British variety, found by Andy Knott and his group of volunteers. Today, we'll attempt to clone it again – to make an exact genetic copy of that individual that will help perpetuate its genetics. 

Knott had demonstrated the technique for us earlier in the session. First, with clean hands, I pulled apart the mushroom, revealing a marshmallowy, white and, most importantly, sterile interior. Then, hunched next to an air filter which helps take away airborne contaminants, I use my scalpel to cut away a small nugget of white flesh, about the size of a sesame seed.

Next Knott opens an agar plate, and I push the piece I've speared on the end of my scalpel into the jelly. I quickly close the lid and Knott seals up the sides with tape. It's done – if I've managed to keep everything clean and I keep it somewhere warm and dark, I should be able to admire a fresh culture of native Pleurotus ostreatus in just a few weeks. When I got home after the festival, I put it under my boiler, the warmest, darkest place I could think of.