A research project that started with the question, 'what was the average person in Britain eating 500 years ago?', and resulted in a rich knowledge base of over 1200 native and naturalised plants with food uses. The vast majority of our modern foods originate overseas, introduced to Britain by colonialism and Victorian exploration, and the global human diet now contains less than 100 plants, with limited biodiversity. Starting from the BSBI's database of native and naturalised plants, over the course of 3+ years I painstakingly reseached each entry for historic, archaeological, or ethnographically documented food uses. This body of ancestral knowledge could help provide local food resilience, reduce the impact of the plants we eat, and better protect food supplies from climate change, pollinator loss and disease. The research is still in its raw form as a giant spreadsheet, so the first part of the talk will focus on the process of research and identification, and some of the trickier questions such as the difference between a food and a medicine, what level of toxicity is tolerable, and how to really define a native plant. The second part will focus on some highlights of the results, including obscure disused vegetables, native things you can still forage, lost recipes for brewed alcohols and psychoactives, vegetables we've bioengineered for edibility, some exciting natural poisions, and addressing whether or not lettuce really exists.