"You found all those things in the trash?" one of the kids in the audience asked with obvious admiration.

Onstage -- amid broom handles, tousled mop heads, light sockets, broken umbrellas, old boots and bicycle parts -- Debra Wise andWes Sanders have just ended a performance of "Junk" to openthe 1980-81 season of Smithsonian's Discovery Theater for children.

"Do you recognize this? It's a junked gasoline tank from a car," Sanders said, as he beat a rubber-ball-tipped dowel against the reverberating tank. Then from bookshelves for another sound.

Wise and Sanders, young theater people with lively and inventive imaginations use puppets andjingles as well as their trashy props for their 40-minute show. While the kids in the audience have fun watching trashrecycle into characters like Rabbit Ears and Electrolux theDragon, they get a lesson about consumerism and ecology. But they might not realize it within the story line.

As a rope-skipping young girl, Wise sets out to buy a birthday gift for a friend with $3. She ends up in "The Bigger Better Buys Department Store," where a salesman -- his head framed by a TV set without the screen -- tries to persuade her to buy more and more on a junior credit card.

She escapes to find Tinker, a chap who has a marvelous collection of discarded items from trash cans. From them he has created delightful characters like Rabbit Ears (made of an old boot, TV antenna and more) who has suffered from "commercial attacks," and Harried Housewife (broomstick, mops, light sockets for eyes and a squegee mouth.) The young shopper finds she can create a gift herself from her family's discarded toaster, a dust mop and some other household items thrown in the trash.

Wise and Saunders and their Underground Railroad show are in residence at Smithsonian until Nov. 2. Performances are given at 10 and 11:30 a.m. Wednesday through Friday and at 11:30 a.m. and 2 p.m. on Saturday and Sunday. While watchingthe show, the youngsters in the audiences can loll and stretch out on carpeted terrance steps in the Discovery Theater,located in the Smithsonian's Arts and Industries Building.

November will bring the New York Pantomime Theatre to Smithsonian in a show called "Spaghetti." Then in December, theLittle Theatre of the Deaf will peform a grab-bag of short plays, including Dylan Thomas' "A Child's Christmas in Whales."