Food of course.
Even as young as almost five. I have two examples.
I came home from the store last week and Hudson started rummaging through the bags and found a bag of chex mix (I usually don't buy that, but it was on sale and my parents were coming) Hudson saw it, let out a audible gasp, and ran over and hugged my leg for a good solid minute. He then looked up and said, "your the best mommy ever."
I was cooking the other day and Hudson was completely engrossed playing with tinker toys. The kind of play where kids mumble to themselves and the roof could come crashing down around them but they are so involved they would never notice. Evidently some smells can take them out of this play trance because all of a sudden as I had meatballs frying on the stove Hudson suddenly stops and looks up. He says, "that smells soooooooo good." I said, "yes it does." Then he says in a breathy voice, "mom, I just love you so much."
So all I have to do to qualify for mother of the year in Hudson's eyes is feed him well.