Language is failing Beryl Dusinbery. She is 99 years old and having trouble retrieving words. “One minute she has a word, then she hasn’t. Where does it go?” Conversely, Shimi Carmelli, 91, can’t forget.

The assignment: Craft a novel from the literary equivalent of found objects. Consider the narrative possibilities contained not just in letters and e-mails, but in school report cards, emergency room bills and police reports filed by night managers at Westin Hotels.

There are the rich and there are the very rich, and while the very rich exhibit varied demographic characteristics, the family at the center of Jenny Jackson’s sparkling debut novel, “Pineapple Street,” is of a highly specific sort: the pedigreed, never-touch-the-trust-fund-principal, tennis-playing, old-money-Brooklyn WASP.