I just discovered this website today,
https://strictlymedicinalseeds.com/https://strictlymedicinalseeds.com/product-category/seeds/medicinal-herb-seeds/I'm going to set aside some of the farm budget to get some seeds and experiment. So far New Jersey Tea (Ceanothus americanus) is on the list of things to get. I'd like to try growing Greek Mountain Tea (Sideritis syriaca), but it seems it is only hardy to zone 7 in the USA and zone 6 in the UK.