Phyllis,
Just wanted to make sure you are aware that for most peach varieties, there will be some genetic variation when starting new trees from peach pits. So your statement above is actually backwards. In other words, you won’t necessarily get a black boy peach from a black boy peach pit. But you will get a black boy peach from a black boy grafted tree.
If you want to be certain to get a black boy (or Contender) peach, you’ll need to graft a tree using wood from the variety you desire to duplicate.
There are plenty of reasons people grow peaches from peach pits. It can be fun to “experiment” to see what you get from the pit, but it won’t be a duplicate of the peach from whence the pit came.
An exception would be a peach called Trugold. It has been specifically bred to be a highly homozygous peach so that it will come true from seed.
Here is a link to an old discussion about the heritability traits of peaches.