Can you over feed a toddler?

jane
My MIL seems to think that you cannot over feed a toddler or baby. She seems to think that they should be feed every 30 mins since they're not like dogs and are actually hungry instead of just eating to eat.  I find that crazy, I think 3 meals a day and a few snacks in between meals is plenty. We buttheads quite abit on this since she believes that I don't feed my son enough because after a meal I don't try and make him eat more food a few minutes later.  I could be wrong on this but I'm pretty confident I am not.  I understand she only wants the best for her grandson but at the end of the day I am the mother and I feel as if that's way to much food. What do you ladies think? How much do you feed your children?