I WAS ONLY trying to save money - somewhere around $300 to $400 - when I had the load of rocks and hard clay dumped on top of my garden. I admit, and everybody agrees, it was a mistake.

We were putting in a swimming pool. For five years - to save money for the pool - we stayed at home, sweltered in the heat and read glowing accounts on how they put in a swimming pool for merely $750. But when the time came that we had almost enough money, it was obvious that the almost-money did not cover such frills as underwater lights, pool covers, pool sweeps and having the dirt hauled away.

So I spoke up and said, "South of the porch - where the garden is - seems several feet low. Why not dump the dirt there?" It would be pleasant to report that I had no intimations of disaster. But everybody said, "You'll be sorry." Luzenia Eccles, my expert on everything, was particularly upset. "Woe, woe," she warned at every mention of the project. But that was because she had spent some three summers working on the garden, adding fertilizer (which she'd brought in her shopping bag from home on the bus), digging in it for hours at a time, weeding it and rejoicing in the tomatoes. Joseph Bauer, the plumber, had already shaken his head over the whole idea.

"You're right by Rock Creek Park," he said. "And they don't call it Rock for nothing."

But I prevailed. And so it came about that when they dug the pool, the dirt - all 12 feet by 36 feet by 5 feet deep of it - was dumped right where the tomatoes used to be. As the backhoe dug, you could see the stratified layers, and that's when I began to worry. First came the good topsoil, black and verdant. Then came what was old fill - rocks, broken brick, petrified timbers, huge boulders apparently left over from the Ice Ages, bits of glass and perhaps a dinosaur or two. By this time I couldn't look too closely. Under all that was clay, or rather adobe, compressed so hard, we could have cut it in chunks and built a house from it.

All this was piled on top of the ex-garden in a clay hill that, to me, looked like Mt. Everest. The daughters thought it was great and had their pictures taken, standing on the top and waving their hands. There was some talk of a flagpole at the peak. It stayed that way until the pool was finished, altered only when the rain washing down the side spread the clay in the hitherto unsullied grass on the lower lawn.

Then the backhoe operator, at my plea, packed it down until it was just a foot or two higher than the land had been before. But the rock, boulders, dinosaur bones, clay and trash were all compressed like cars compacted into scrap metal. "All we'll have to do," I reassured my family, "is to rake the stones out. We can make walks out of the stones. Or a rock garden."

Rock garden it was - all rock. The daughters, and a succession of neighborhood young men (at a dreadful cost), tried to rake it. But the combination of clay soil and rock had made a sort of natural exposed aggregate concrete. You couldn't rake the rock out.It seemed likely you couldn't blast it out.

In despair, we called a couple of young men who advertised in the paper that they would Rototill gardens. They called several times, declining to come when the soil was wet on the basis that it would all compact. Finally, they arrived with their peat moss, Rototiller and hope. They positioned themselves, started the tiller - and nothing happened. It just stood there.The men, first muttered politely, then louder, their words and their voices increasing in strength. And nothing happened.

At last, taking turns, they got the tiller to go a few feet, hitting rocks every 6 inches. The rocks flew everywhere - crashing against the tiller, imperiling the workers, and landing in new positions in the garden. After a brief time, the Rototiller men declined to go further, and took the position that we owed them the entire agreed upon price since it was obvious the rock was all our fault, and who knows that dire damage had been done to their tiller.

That year the garden (ha!) stayed as it was, in its barren, scorched earth condition. It might have been rented out to movie people in need of a Vietnam set. Whenever it rained, though, the garden became an impenetrable quicksand bog.

Remember the Labor Day of the Gully Gusher? We'd invited a large group - parents and children - to daughter Camille's birthday party.An hour before they arrived there were 6, no 7 inches of water in the basement. All available hands were down there bailing. Sofas floated across the floor. Magazines and newspapers sunk with a gulp and a bubble. The antique (1850) square grand sat helplessly, her pedals and lyre like some submerged treasure. Unplugging the light fixtures and the television set was reason for terror - the person doing it expected any moment to be electrocuted, despite rubber gloves and soles.

In the midst of the 20 maids with 20 mops, a telephone call came from the neighbor on the low side, who represented an Oriental temple. "Please, make your mud quit washing into our garden. It is not nice for our flowers," she said. "Dear Lady," I replied. "The only thing I can do is to suggest you pray to the Good Lord to make the rain stop." All right," she said. And in a few minutes there was a great pounding of the temple drums. In 15 minutes, the rain stopped.

The next summer, my husband decided we should work like Middle Easterns peasants, who are alleged to farm rocky soil. So he built a sieve - a square box bottomed with wire. We took turns digging soil, shaking it in the sieve and dumping the rocks down the side. We managed to make two vegetable boxes that way. One has been quite successful for the strawberries.

Last year, we found an older, braver Rototiller man with nerves and tiller of steel. He plowed the rest for us, and we planted tomatoes, jalapano peppers, corn and spaghetti squash. The poor plants struggled as best they could, but the results were so dreadful looking that even the birds and the squirrels turned up their noses at them. Only the bees and the flies seemed pleased.

This year, we agreed, we weren't gardeners. We'd let it go. But suddenly, the garden (ha!) had ideas of its own-producing an immense crop of rare and exotic weeds, probably from rock seeds. It became a terrifying jungle. The daughters refused to mow it for fear of tigers. We imported professional mowers - they declined for fear of ruining their mowers.

Finally, with vast sums of money, we enticed a splendid gardener, a high-school lad, to mow the lawn - including the garden. He first cut it down with a machete, fearless in the face of the wild life that could be lurking below. Then he mowed it. And a stone sprung up from the ground and shattered the patio door. It cost $153.50 to replace.

For next summer, my husband has The Final Solution. He's going to dig up the entire mess and make a lily-pond. And have the dirt hauled away.