Teresa Meyerhoff was in the winner's circle. Harry, her millionaire husband, was on one side of her, the governor of Florida on the other. The just-won silver Flamingo trophy was held just high enough in the air to pick up the flinty beams from her diamond earrings, diamond brooch and almond-size diamond ring. Clustered in front of her were the ABC television cameras and dozens of reporters and photographers. The cameras were clicking on the Meyerhoffs-he, younger than he looks, she, looking younger than she is-both smiling triumphantly for all the world too see.

Never mind that the track has fallen on hard times, and never mind that the pink and white "geraniums" spelling out "Hialeah" in the winner's circle were made of plastic. Teresa Meyerhoff was the winner's circle here last Saturday, in there with her 20 percent share of Spectacular Bid, the horse that had just won the Flamingo Stakes, a horse that is insured for $12.1 million, conservatively valued at $20 million, a horse that just about everybody says will win the Triple Crown, Teresa Meyerhoff, of Easton, Md., has arrived, and to do so she has had to come a very, very long way.

Teresa Meyerhoff is the mistress of Hawksworth these days, a 320-acre estate on the Eastern Shore.

She is the wife of a Baltimore construction magnate who enlarged the family's original fortune so much that he can comfortably state that owning the world's potentially most valuable thoroughbred will not alter his way of living. At 31, Teresa is beautiful, and very rich. She is light-years away from the dairy farm in upstate New York where she grew up, and light-years away from the Baltimore bar where she was working to put herself through college when Harry Meyerhoff walked in five years ago.

Hers is not merely the story of a poor working girl who falls in love with a wealthy man who takes her away from it all. It is also the story of a young woman, who with her husband and stepson, plunked down $37,000 on a horse two years ago, then watched that investment multiply into a fortune in the chanciest sport there is.

When Teresa Meyerhoff was growing up, little girls dreamed of marrying well and living happily even after. They also read the Walter Farley black stallion books and dreamed of owning a great racehorse. Teresa Meyerhoff is riding the crest of both those American dreams right now and will ride wilder and faster as the Triple Crown races begin and the publicity around her horse grows more frenzied.

Teresa Meyerhoff has a tight grip on her extraordinary situation. She is getting ready for the Kentucky Derby and she is enjoying every minute of it. Or, as she puts it, she is very much in love and "incredibly" happy. "I was before Spectacular Bid. He just adds excitement. Next year we'll be has-beens."

Harry Meyerhoff says they are private people. She says they don't live ostentatiously, and that certainly seems to be true. With his faded blue jeans, tennis shoes, pepper-and-salt beard and ever-present beer or vodka, Harry Meyerhoff, 50, has to be the most laid-back millionaire to own a thoroughbred racing star in years.

Equally unpretentious, she shows up at dawn for the horse's prerace workout in tight Sassoon jeans that show up her tiny waist, a green blouse, mules and a smudged white purse. In the winner's circle, where most women would be dressed to the nines, she wears a no-name blue knit dress, lots of diamonds and the same smudged purse. During an interview in her hotel suite, she wears a green caftan and sits propped up in a chair, her bare feet curled under her. She smokes occasionally and sips vodka. She wears almost no makeup. Her shoulder-length ash-brown hair hangs straight, framing her large deep green eyes. She smiles quickly, easily, and has a good sense of humor. There are certain subjects she treats delicately, such as Harry's first marriage an divorce, but most of the time she is straightforward, candid.

The second child of Henry and Alice Riberdy of Waterford, N.Y., Teresa was married and pregnant in her senior year in high school. "That was 14 years ago," she said. "You didn't stay in school if you were pregnant then. I was lucky. They let me finish at home and get my diploma." Fourteen-and-a-half months after she gave birth to her first son, her second son was born, and she went to work while her husband went to college and her mother took care of the children.

There in the billing department of the local phone company, she got her "introduction to unequal opportunity. I was doing the same job as a young man who was making more than I was. He was hired at the same time I was. He was a bachelor and I was a mother of two. That was 1967-1968. I don't think that was fair. But it was better than nothing."

She and her husband moved to Baltimore in 1968. He enrolled in the Peabody Institute. The marriage lasted two more years, and she ended up with the two sons, a high school diploma, and an absolute certainty that there was more to life than she had seen, and an equally sure determination that she was going to see it before it was too late.

Her first step was to send the children to live in Florida with their father's parents. "It was a very difficult decision to make," she says. "They lived with their grandparents from the time they were 5 and 6 years old until 1977. I missed those years with the boys, but it was something I wanted to do. I wanted to go to school, to learn to be on my own. I've talked to them about it. They're not bitter.

"My parents wanted me to come back to upstate New York with the children. I knew it was wrong. One can get smothered by parents wanting to do good things, smothered into another dependency.

"My parents didn't understand it. We were a close, Catholic family in which the family is seen as kind of sacred. It was difficult to explain that I felt the same way, but that I also felt I didn't know who Teresa was. I'd gone from being a child to being a wife and mother. I thought I'd failed as a wife and I didn't want to fail as a mother.

"I'm not an unintelligent person," says Teresa Meyerhoff. "I think I'm a very intelligent woman. I knew there was something more and i wanted to find out what it was before I lost all opportunity."

Friday: Teresa finds work at O'Henry's restaurant and is tending bar the day Harry Meyerhoff walks in .