That does not look like a mammal tooth. I'd like to see the root end of it. Any more photos?
Uh oh. Have you discovered a piece of the elusive pine shark?
I really can't help you. However, I would hope you would keep encouraging your son to continue to look around when he walks in the pines. Finds like his come from doing just that, and hopefully he will continue to become better at it. He obviously has the skills and just needs to continue practicing. I see only good things coming from him in this regard. Well done!
Guy