Sylvan Street by Deborah Schupack

What would you do if you found a million dollars in your backyard? Well, Billy Cane finds that large amount of money in his shed during a pool party with his neighbors on the cul de sac of Sylvan Street in Ashley-on-Hudson, New York. He decides to share his secret and the money with each family. There's retired couple Sally and Janic Levlovic, Jen and Keith Margolis and their brood of five, single painter Ash Flemming, and the newcomers, the Yaniv-Hansens. Some have reservations about keeping the money. Soon, though, everyone agrees to take it, even though they all agree not to go spending beyond their original means. But the cash is a great temptation and lives begin to change. There's also the fact that someone hid the money there in the first place and might come back for it...