I agree Scott my peach seeds also seem to grow themselves. I have read seeds from earlier varieties (as well as donuts) don’t germinate that well naturally, but I’ve seen seedlings come up under just about any peach tree. Still, when I gather seeds to plant in a row, I try to gather from varieties after Redhaven.
I’ve had good luck growing my own apple rootstocks by just gathering a bunch of seeds and putting them in a plastic bag in the fridge, then planting them in the spring.
I’ve not had any luck germinating plum seeds, but I’ve not tried planting very many.