Fortunately, good sense carried the day and I recognized that that my son, bless his heart, 1) saw and recognized basil in a container that did not actually say basil, 2) remembered that basil is a key component in a traditional pesto and 3) did not ask me to make him pesto for lunch but rather asked if we could make it together and 4) unlike many of his pals, will actually eat something that doesn’t actually look all that great (green + slimy is so attractive to eight year old boys in so many ways but why not in the form of food?). After only a moment’s prevarication, I decided that these points ought to be rewarded. We bought the basil.
His job: everything. He stemmed, rinsed and dried the greens, shredded the cheese and figured out proportions of nuts, garlic, oil, salt and pepper, grinding and tasting his way to a rather nice sauce.
A mom could get used to this. And if it's true what some guy in the New York Times said about pesto maybe being a wee bit less than au courant, I suggest humbly that he run out at the earliest opportunity to find himself an unjaded eight year old for whom pesto is less a cultural touchstone and more just a delicious lunch he can make (mostly) by himself.