The usual outdoor furnishing that contains a storage space is an outdoor bench. Instead of the usual plank of wood with two legs on both ends, outdoor benches these days have boxed structures which can be equipped with drawers or a top-removing lid. You can store whatever knick knacks you need to spruce up your backyard for your own or party use.
While many would say such decorations and added detailing for the outdoor furniture can be stored inside the house, it would be a complete hassle to go back and forth indoors especially when the outdoor space is frequently used. You don’t wish to go trudging in and out in the afternoon to bring cushions to your outdoor seats. Or, have to fetch table linens or placemats from your stock room when you decide to take dinner al fresco every day.