My son didn't like to eat walnuts....so can I give him thru mixing in his milk?

Ofcourse you can grind them and mix them in milk to give to your son. And even if you soak them, they taste good. But any which way, if your son likes it mixed in milk, you can give him this way too.

Yes, sure. You can. You can also do one thing. Dip the walnuts like we do almonds in the water at night and in the morning peel their cover and may be your son would like the taste that way.