For those interested, Google on "heirloom seeds";
it makes for a good start.

As of 20 years ago, there were networks of people
trading seeds. Some would volunteer to maintain a
certain seed strain, which some of you might do.

I got my heirloom seeds from a local guy at a Living
History type place. Every state has these I suspect,
and many of these have heirloom gardens. Also, you
can check your local Gov. Ag Agent ( sometimes staffed
by volunteer gardeners) who can give you local sources
of heirloom seeds. Using Local Heirloom Seeds can save
you a lot of research, time, failures. Mine worked as
good or better than hybrid seeds.

Some seed types are easier than others to maintain,
as a pure true strain. Corn is hard to isolate, because
the pollen can blow with the wind for hundreds of yards.
Beans are easier, because they do not cross pollinate
so easily.

Hike4fun