Nyumalums is a candy bar, presumably produced by Nyums.
It appears in "Mabel's Scrapbook: Heist Movie." Mabel brings a bar into the theater and drops it, causing the Pines family and Soos to get kicked out of the theatre by Thompson. Later, while watching "Pony Heist," Mabel brings a bag of these and eats it.
They come in a bar or bag. They are light blue with blue dots and a yellow bubble letters logo of the word Nyumalums.