Julia, my guess is that the first pics. are a type of Rudbeckia or Black Eyed Susan, in which case you can follow the directions in the FAQ of this forum. The other plant looks like an Amaranthus, but I have no experience with saving seeds from that plant. Good luck.

Thank you for your guesses.

I checked out Rudbeckia and many of the pics look like what I have. The FAQ's for the Rudbeckia seed saving helps a great deal.
My sister insists that the plants are being seeded by birds but whatever did it, I'm grateful.

Your guess on the Amaranthus looks to be what I have growing in there. Can't figure that one out as to how it got there but will do some searches/google for seed saving.

Many thanks for clearing up the mystery.

Julia

A lot of the Amaranthus I think have little black round hard seeds near the stem. When they are heady for harvest, pick the blooms and put in a paper bag, and shake them loose. If you do indeed find the black seeds, you can then scrape the faded blooms off of the bloom stalk, and get more of them loose/free. I then sift the seeds out of the chaff via a metal mesh strainer.

Sue

The purple plant looks like Hopi Red Dye Amaranth (Fedco Seeds). I planted once and unfortunately let it go to seed and now its a weed, albeit a pretty weed. My plants leaves are a darker purple than your picture and will grow over six feet tall and three plus feet wide. When young the greens are edible and add color to spring salads,

Thanks for the follow-ups.
It may be Hopi Red Dye Amaranth. Will try to collect the seeds and see what happens next year.

Julia