John Lawson vividly remembers the moment a butter-yellow ice cream truck first turned up in New York’s Tribeca neighborhood in 2008. Ben Van Leeuwen had just launched his eponymous ice cream brand with his brother Pete and now ex-wife Laura O’Neill.

At the time, Lawson managed three Whole Foods Market stores, including the one in Tribeca. After sampling the ice creams and “nerding out” on “a very specific Italian pistachio,” he recalls begging Van Leeuwen to expand his new venture into grocery retail. Though it was early days, Lawson could see the potential beyond scoops. Three months later, Van Leeuwen pints appeared on a shelf. Today you can find them in more than a quarter of all supermarkets across the country.

Lawson is now one of just nine buyers responsible for scouting local and emerging brands for more than 500 Whole Foods locations in the US, Canada, and UK. As a 20-year veteran of the industry, he’s amassed an encyclopedic knowledge of what ingredients, product names, package design, and price points appeal to consumers.

Grocery buyers like Lawson can wield outsized influence over what we eat. They decide what millions of consumers add to their carts at more than 45,500 supermarkets across the US—and their choices can turn an unknown brand into a household name overnight. I spent one fall afternoon trailing Lawson to see what makes an item shelf-worthy in his eyes.

Our day started at the Whole Foods in Gowanus, Brooklyn. From the moment we meet, Lawson is bursting with facts about the coffee, condiments, tortillas, and hummus lining the shelves, which he can’t help but straighten up as we pass by. He casually rattles off the years that each product launched, in what stores, and when they expanded nationally. “It’s like going to a party,” he says. “I have to introduce you to all my friends.”