New Italian Restaurant & Piano Bar Openbr br Mammoni Cucina Rusticabr 17 S. Morton Ave., Morton, PAbr br By BARBARA ORMSBYbr Delaware County Daily Times Correspondentbr br MORTON PA— If you are standing on a clay-colored faux stone sidewalk at 17 S. Morton Ave., in front of a bright yellow facade, you've made it to the borough's newest restaurantentertainment venue. Jolly's Dueling Piano Bar and Mammoni Cucina Rustica. 610.690.