I had a peach seedling that came up in the compost.
Just so that I didn't have to kill it, I planted in an out of the way spot. After 3 years, it produced a tiny crop of apricot-sized peaches. Surprisingly, they tasted good -- white peaches!
Last year, there were about 15 peaches. I had thinned them and they were a little larger.
This season, the tree's fifth year, I picked over 2 3-gallon buckets of small peaches off that tree! The squirrel had regularly picked off green fruit and I relied on him to thin them. He didn't do a very good job of it

.
I showed one of the peaches to an orchardist. She said that it looks just like a Blushing Star white peach and that I'm very lucky. Her husband had told me that the trees in orchards are all clones. A seedling would be a hybrid but it
could turn out okay as a fruit tree.
My problem with this tree, other than that it broke a branch from the weight of so much fruit this year :/, is that I planted it very near the east property line. I am not sure how to prune it! Really, I wasn't thinking that it would have any value and that I would be taking it out after it made the first of whatever fruit that it was going to make.
I agree with Bid: from what I understand, it is a real gamble and it turned out to be just dumb luck here

.
Steve