My family only grew one variety of anything that might hybridize in any one garden. Aunt would grow popcorn, granny would grow sweetcorn etc. Similarly, squash, pumpkin and the like.

Thanks Albert!

Thanks Rodney, that's helpful info.

The Organic Seed Grower: A Farmer's Guide to Vegetable Seed Production

This book has some good tips I am told (just ordered it, so cannot confirm yet), Also check our "Real Seeds" Website (UK Wales) they have a good way and info and a good book.

IMO before gardeners became collectors, and when garden produce was a more important part of the diet than it is now, people just found one variety that suited their needs & stuck with it year after year. Crossing probably was not much of an issue. When something new popped up (due to a mutation or inadvertent crossing) they saved seed if they liked it, and tossed it if they didn't. There weren't many written sources of seed saving info until fairly recently, so other than anecdotal wisdom, seed saving for many years was most likely trial & error.