This is the wild form of melon Cucumis melo known as Queen Anne's pocket melon. It's about the size of a snooker ball and grows as a weed in melon fields in the US. It's edible but insipid. The main reason for growing it, apart from its ornamental properties, is its incredibly intense melon fragrance. One ripe fruit, which lasts for about ten days before it goes soft, will perfume a whole room. Apparently Victorian ladies used to carry them around in their pockets, as a kind of portable pomander. I've grown it for a few years and found that it looks particularly striking in a hanging basket in the conservatory, where the fruits can dangle down like striped orbiting planets. The plants are quite compact and carry separate male and female flowers, so it pays to deliberately pollinate the female flowers to ensure fruit set. Each plant generally produces about half a dozen fruits. The seeds are hard to come by (I got mine via an exchange with a Dutch botanic garden) but I see from a quick Google search that there are a few suppliers in the US.