Sissy Spacek was musing about what it's like to visit the West Coast.

"It's a funny thing," she said with a smile. "Sometimes when I come back to town, people see me and they act as though I should be 100 by now, they're so shocked."As a matter of pure fact, Spacek turned 41 on Christmas Day and she looks a decade younger. What confuses the locals is that she does not frequent the Hollywood scene. She and her husband, director Jim Fisk, make their home on a 210-acre horse farm in rural northern Virginia.

"I'm sure there are things we miss out on," she said, "because there are a lot of deals made over lunch and dinner. Those things we miss, but what we gain is more important."

Spacek's belief in home values is demonstrated by her four-year absence from the screen. The reason is motherhood. "I have a 2-year-old daughter in addition to an 8-year-old daughter. That sidelined me for a bit. But I'm back!"

She returned last month in "The Long Walk Home," co-starring with Whoopi Goldberg in a fictional drama based on the 1955 Montgomery, Ala., bus boycott to fight segregation. Spacek has also completed another film, "Hard Promises," a romantic comedy with William Peterson.

"The Long Walk Home," which had a December release in Los Angeles to qualify for Academy Award consideration, has aroused flak from some black leaders for telling the bus strike story from the white point of view. Spacek plays a Southern matron who defies her segregationist husband to drive her domestic, Goldberg, to and from work.

The script appealed to her, Spacek said, "because this was part of my life. I spent most of the '60s fighting the '50s values. . . . I loved that the story was told through the eyes of a child, because that's how I observed it in the '50s."

"I loved the relationship between these two women and how they had an effect on one another. I loved the idea that this huge event, the boycott, is just a backdrop. The story is how it affected these two families, black and white. And I loved that each family got the same attention in the story. It really made me feel for the first time how the civil rights movement affected the lives of just everyday people."

She observed that the people who suppressed blacks seemed to be upstanding citizens. "And that's scary, because we all become responsible for that in a society. Even if you're a good person and you don't do something you're aware of, or even if you're not aware of it, you're guilty of repression."

Mary Elizabeth Spacek (her father was of Czech origin) was reared in Quitman, Texas. Her two older brothers called her Miss Spacek, a name she never gave up. Her childhood was full of the joys of rural life: frog hunts, horse rides, cheerleading, 4-H Club, etc. Also an undertone she became aware of later.

"I was just a child, but I have vivid recollections of the segregation: separate entrances, seating in the theater, bathrooms, drinking fountains. I remember all that," she said.

"People where I grew up were not as economically set as the upwardly mobile characters that we portray in the film. But yeah, I think it was prevalent, certainly in the South and the Southwest.

"When I was in high school or junior high school, that was when integration started. But I knew quite a number of black children, all of whom were the children of domestic help."

To spare her the grief of watching a brother die of leukemia, Spacek's parents sent her to New York to spend the summer with a cousin, actor Rip Torn, and his wife, Geraldine Page. She made a stab at being a rock singer but returned to Quitman when her brother died. Returning to New York, she tried with minor success to find work as a country-rock singer.

Spacek made her film debut at 20 in "Prime Cut" with Lee Marvin and Gene Hackman. Her role as the young victim of a white slaver presaged the offbeat roles that would mark her film career. In "Badlands," she was the teenage sweetheart of mass murderer Martin Sheen. Then came the starmaking "Carrie" as the mistreated high schooler who uses kinetic powers to zap those who have wronged her.

"Carrie" brought the first of five Academy Award nominations. Others were for "Missing," "Coal Miner's Daughter" (she won as country singer Loretta Lynn), "The River" and "Crimes of the Heart." Her last film, "Night, Mother" with Anne Bancroft, came four years ago.

Spacek has no misgivings about staying on the Virginia farm: "Knock on wood, so far it has worked out beautifully. We really love it there. But we particularly enjoy being here in January, February or March. We stumble over each other to get to L.A. in the dead of winter."