Our medieval recipes call for some interesting ingredients. Galingale? Grains of paradise? Here are some helpful vendors who will a) know what they are and b) probably have them for sale.
Asian markets often have our ingredients. If you don’t live near one, reach out to a fellow SCAdian who does.
Nota bene: investigate your recipe’s ingredient list carefully. Some medieval recipes include poisonous herbs! We don’t know whether they didn’t use them in sufficient quantity to kill anyone or what. Be safe, be sensible, replace those with something similar but not toxic.