Comment by runjake
Good to know. I'm trying to dig up direct links to those USDA guides.
I mostly value the Encyclopedia of Country Living for it's old world skills (canning, food preservation, etc), but I'm fortunate also to live in a rural area with a lot of farmers and I have ready access to relatives and friends who are well-versed in those old world skills and they've been happy to teach them to me.
Best resource are the people who lived it. My grandfather was 102 when he passed and (when I could get him to stop talking about world war 2 for five minutes) filled in a lot of blanks for me in old time food storage.
My number one piece of advice for people learning this stuff: Nursing home activity staff know who the residents are who grew up on farms and in the country and are DESPERATE for volunteers. Go to a home and ask to spend time with those residents. That's what I do. It's how I learned most of the wild craft skills I have. The residents love it, it helps the community, and you learn.