Dear Mary:
  When I was younger I loved chicken hearts, gizzards and livers.
Livers pop like mad so you would want to put a screen over the pan, but
they can all be cooked the same  as the heart.  Know in advance though
that the gizzards are very "chewy".  They will keep your son busy for a
long time.  You may want to cut them up a little since you can choke on
them.  Chewing may take longer than he wants.  Another item (and I am
loath to mention it here, but speaking of my childhood reminded me) is
horsemeat.  I love horses, but you used to be able to get packages of
frozen horsemeat for dogs.  We would simmer it with a little water to
thaw and cook it all at the same time.  One of the things I remember
most about being a child is always being hungry.  So I would sneak
little pieces as it was cooking and I still remember it as being one of
the most tasty meats I ever ate.  No we weren't poor and my mom fed us,
I just always seemed to be hungry.  I grew 3 inches during one 3 month
period so I guess that could be one of the reasons.  Back to the meat.
I don't know if it is available anymore, but you might want to look into
it.  God knows they still kill plenty of horses, but I think they send
the meat to Japan.  Hope I haven't upset anyone. I wish I could get my
step daughter to make such efforts for her boy.  He is almost 13 and his
"behaviours" and size will mean that he will be "unsuitable" for family
life soon.  Bless his little heart, he never had a chance.  (Here come
the tears.)
Beverle