For generations, kids across New England have grown up with the sticky-sweet, snow-white confection known as Marshmallow Fluff. These days, however, there's a hint of sour at the Lynn headquarters of the key ingredient behind the classic peanut butter-and-Fluff concoction known as the Fluffernutter.

Durkee-Mower Inc., longtime maker of Marshmallow Fluff, has sued William-Sonoma Inc., ordering the kitchen-furnishings retailer to stop selling tins of a candy bar called the Fluffernutter, a name 86-year-old Durkee-Mower trademarked in 1961. Williams-Sonoma has until April 14 to respond to the complaint in US District Court in Boston.

''They're trying to trade on the nostalgia for the classic Durkee-Mower product without acknowledging our trademark rights," said Durkee-Mower attorney Peter Sloane, who specializes in intellectual property law at Ostrolenk, Faber, Gerb & Soffen in New York. ''To me, it's a flagrant violation."