Betty poked her head out the window of her second-story Glover Park apartment and seeing the crowd assembled in the Saturday- morning sunshine decided to bring down her giant inflatable plastic frog, her Spanish leather wine decanter and a set of punch glasses that had long lost their bowl.

Meanwhile, downstairs in what once was my apartment, a family of sari-clad Indians repeatedly plugged and unplugged my toaster oven in the dining room, muttering darkly. In the bathroom a young woman wriggled into a pair of my jeans. On the back porch a stocky man with a knapsack ogled my wood-burning stove, and on the front lawn -- the main arena -- Mongol hordes pawed rapaciously through myriad cartons of my belongings.

This spectacle was my yardsale. Cash for my trash, as the Fats Waller song says. Only I wasn't too sure.

My pack-rat instincts protested piteously as old treasures vanished forever in the hands of strangers. I reminded myself of the size of the suitcase I was taking to California. The old oak ice-cream maker had to go -- and much else besides.

It had all started two weeks before, when the ebullient young couple who were taking over my apartment stopped by to see how my packing was progressing.

"I just don't know what I'm going to do with all this stuff," I said, miserably surveying the boxes of wretched excess.

"Well, Jay and I have lots of stuff we want to get rid of -- although not nearly as much as you. But we could have a yardsale," Kathy brightly suggested.

We agreed on a weekend two weeks away. I suggested a two-day sale. Whatever didn't sell Saturday we could mark down and unload Sunday. On Monday we'd call Goodwill.

Neighbors who heard about the plans asked if they could join in. The sale I'd dreaded was turning into a potential block party and possibly even fun.

As an inveterate collector of Things I was an experienced Washington yardsale-goer. The experience easily translated into yardsale-giver.

Wednesday before the sale was the day to phone an ad in to the paper and put up signs. One must put up signs early enough for yardsale regulars to plot their weekend course, but not so early that the signs deteriorate beyond legibility before the sale.

Armed with cheap white paper plates, thumbtacks and a rainbow of felt-tip pens, my neighbor Pam and I made 20 signs and put them strategically around the neighborhood, particularly at the bus stops, where we had a captive audience.

Friday I bought little white stickers and started pricing items. Mistake. Put a price on the little wooden case, shellacked by my father, that I'd carried to art class as a child? My high school ice skates? Task abandoned. Just haul it all out there tomorrow, I figured, and let people make offers.

That night I fretted in the wee hours:

"What if it rains? What if no one comes?" I needn't have worried: The alarm had barely gone off when there was an early bird at my door demanding, "Have you got any old prints for sale?" A few minutes later a man who identified himself as a book dealer arrived; he was so anxious to beat the crowd that he carried the cartons of my library castoffs outside for me. Goodbye Williamsburg Cookbook and a dozen others. Hello $6.50. Not a bad start.

Before 10, the front yard was mobbed. The yardsale gypsies were upon us. And it was good. I scarcely had time to utter a price and an item was gone. No time to reflect or mourn. I was too busy ushering people into the apartment to plug in appliances, try on clothes and examine the furniture. My pockets rapidly filled with quarters and dollar bills.

Yardsales can be odd examples in anth wise in the ways of yardsales, I knew this. Everything was priced to sell. Everything except that which I wasn't sure I wanted to sell. "Hey! How much do you want for this here bookcase?" a young lawyerish-looking type asked.

Oh, no. My little wooden bookcase. I'd found it in a trash pile. It needed painting and one shelf had been partially hacked to fit a pencil sharpener. But I adored it.

"Uh . . . ten dollars --" I stammered. Too high; he won't take it. "Okay. Here you go."

Nonchalantly, he hefted the bookcase and walked away. I almost fainted. I stared at the ten in my hand. What's money? Filthy lucre. Bring back my bookcase!

Betty, my neighbor who is a social worker, sensed my distress. She placed a comforting hand on my shoulder. "Debbie, you can't hold on to everything in life. You have to let go of some things. It's good for you." Yardsale crisis counseling.

By early afternoon business tapered to a steady trickle. More neighbors joined the sale with boxes of unused wedding presents, clothing left behind by ex-lovers and other debris of modern life. Everyone's skeletons were out of the closet. We would never have guessed that Pam even owned imitation ivory toothpicks or souvenir scenic-views-of- Ireland coasters. But there they were, alongside Betty's plastic frog, my cheeseboard and Jay and Kathy's crockpot.

But one person's junk, as they say, is another's find, and as the afternoon sun burned, we began to eye one another's stuff. Jay and Kathy bought Pam's refrigerator magnets. Pam bought Steve's old portable typewriter. Steve bought my set of stoneware dishes. And I, California-bound, wisely bought nothing. I did, however, turn down Betty's offer for my huge canning pot and brought it back inside for storage. After all, you never know. Someday I might want to can tomatoes again.

Slowly but surely, the cartons of stuff dotting the lawn began to empty. People bought things I'd bought at yardsales myself. I began to think of life as a giant yardsale food chain. People were even buying my old clothes. I stared in disbelief as a fashionable young woman donned a faded green sweatshirt my brother once left in my car. "You want that?" I asked. "I think it's neat," she said. "How much?"

Oddly, nice clothes -- wool skirts, a silk shirt, a raincoat -- remained unwanted. But my worn flannel shirts, jeans and sweatshirts were snapped up. I dove back into the apartment to search for more to sell. I was suddenly overcome with selling fever. I wanted to sell everything.

I brought out a long-sleeved antique robe with big shoulders and gobs of lace. A lovely garment that perversely looked awful on me. Yet when a buxom blonde woman slipped it on, the robe took on a whole new look. As did she. At last it had found its rightful owner. She was happy. I was happy. This wasn't so bad after all.

By 5 we were all tired and ready to pack it in for the day. Before we dragged the dregs of the sale inside, I unsheathed my Instamatic and asked a customer to snap a group shot of the tired but triumphant yardsalers. Then I went upstairs to count my money. Two hundred dollars! Cash for your trash. Nothing like it!

EPILOGUE: Sunday dawned to a steady downpour. Too wet to sit out on the lawn with cartons, though yardsale-hardy Washingtonians no doubt would have stopped by. No. We declared the second day officially rained out. But there is a happy ending: All the neighbors had filtered into the apartment where we'd deposited our cartons yesterday. What to do? No one wanted to take their stuff back now that they felt rid of it. Suddenly, a little elderly woman joyfully trotted out in the rain with our boxes. She smiled and promised us tax receipts as we loaded her trunk. End of yardsale.

HOW TO GIVE A YARDSALE: AT LEAST ONE WEEK AHEAD: Sort out items you wish to sell. Make notes of special items to mention in your ads.

AT LEAST THREE DAYS AHEAD: Call an ad in; you may want to call sooner for neighborhood papers with earlier deadlines. Make and put up signs. Paper plates are attention-getting, cheap and sturdy. You will need thumbtacks for trees and telephone poles and heavy tape to attach your signs to metal posts. Be sure to list the date(s), time(s) and address; you might also want to list items like beds or typewriters or categories such as furniture or kitchenware. This attracts buyers who are looking for what you are selling.

AT LEAST ONE DAY AHEAD: Spruce up your sale items -- that is, wash glassware, polish appliances, dust off books to make them look more attractive. If you don't want to put a price sticker on each item, try to estimate how much (or how little) you want for it. Also try to clear off some tables to display small items.

AFTER THE SALE: You can at least recycle what you can't sell by calling places like Value Village, Goodwill or the Salvation Army. Most will come pick stuff up. Also take down any remaining signs.