Lingerie designer Mary Green got the idea in China. She was stunned at the piles of silk scraps littering factories. Why didn't they ever do anything with it, Green wondered.

Then it hit her - buy up all the scraps, patchwork them together and make some crazy panties. "The wilder the patterns, the better," she says.

PHOTOS: Earth-friendly fashions

Brooklyn jewelry designer Jody Lyons has done the same with everything from buttons to perfume bottle tops, creating her eclectic Joli Jewelry line.

Colombian-born Patricia Ordonez has even found new uses for an ex-boyfriend's jeans. "I wanted to promote the green movement and needed something that expressed the idea of reusing the 'Excess' clothing we all have," Ordonez says. Some snips here, stitches there, and the first of her "Made from My Ex's Jeans" tote bags was created.

Eco-conscious folks have a word for this: "upcycling." Old items aren't just used over - they get added value.

To celebrate Earth Day, which marks its 40th anniversary tomorrow, we've found stylish ways to resuscitate old mah jong tiles, audiotapes, even a used Ford Mustang.

Seriously.

GREEN JEANS

Scraps and denim remnants make up the recycled cotton used in Levi's ECO jeans, which includes the men's 511 Skinny (above, $69.50), and women's Low Skinny, Skinny Boot and Mid-Rise Straight. And in all Levi's you'll find new Care Tags for Our Planet, advising consumers to wash in cold and donate used clothes to Goodwill; at Levi's stores, levi.com or call 800-USA-LEVI.

TANK TIPS

You might say Kenneth Cole is environ-mental - he's obsessed with efforts to promote social responsibility and eco-awareness. And he has a way with words. So his new "Is It Me Or Is It Warm In Here?" tank top, $35, is a clever reminder about the dangers of global warming. All net proceeds will be donated to his nonprofit Awearness Fund; at Kenneth Cole stores and kennethcole.com.

A GREEN CLEAN

Turning old finds into a new wardrobe is swell. But how do you keep it clean? Detergent makers are bagging phosphates, dyes - and going green. Method's new laundry detergent is plant-based, and 10 ounces lasts 25 loads ($15.49, at amazon.com). ECOS has coconut-based fabric softeners and cleans a full load with 1.5 ounces ($6.79, Kings Super Markets, Garden City; The Health Nuts, Westbury; ecos.com). And WIN - official detergent of the U.S. Olympics - has a new WIN Green formula, with biodegradable ingredients that target sweat molecules embedded in wickable fabrics ($6.99, at Sports Authority, Dick's Sporting Goods, sweatlifter.com). - Joseph V. Amodio