Once I took a chicken casserole to a Green Acres School potluck supper and nobody ate it. I thought about that for a long time. Mine was just one more in a long line of chicken casseroles and while it tasted fine, it didn't look appealing. It was a lesson.

The time for pumpkins and potluck suppers is upon us again. Schools, churches, organizations and informal groups get together for grand (and often stomach-boggling) times of sharing. Certainly the quality of the food affects the nature of the experience. Ideally, for the cook, the dish offered should be a touch uncommon, quite tasty and fairly easy to prepare. It should be presented attractively on something less fragile than grandmother's china platter.

Here are six recipes -- two main dishes, two salads, and two desserts -- that meet these criteria. They are appropriate for private dinner parties, as well. ROAST PORK LOIN (6 to 8 servings) 1 boneless pork loin (about 3 pounds), at room temperature Salt and pepper to taste 1 teaspoon rosemary 2 tablespoons olive oil Watercress

Season pork loin with salt, pepper, and rosemary. Rub with olive oil. Wrap in aluminum foil.

Heat oven to 350 degrees. Roast for 1 1/2 hours, uncovering for last 15 minutes to allow meat to brown.

Let cool slightly. Cut into thin slices. Arrange on platter and garnish with watercress. LIVER PATE (6 to 8 servings) 3/4 pound calves liver 1 medium onion 5 inches of plain anchovy paste 3 tablespoons flour 3/4 teaspoon salt 1/4 teaspoon pepper 1/8 teaspoon allspice (generous) 3 eggs 1 cup (1/2 pint) heavy cream French bread Cherry tomatoes

Put liver, onion, and anchovy paste in in food processor and work until finely chopped. Add flour, salt, pepper, allspice, eggs, and about 1/4 cup of the cream and work until liquefied. Mixture will be fairly thick.

Rub a 1-quart crock or souffle dish with butter. Force liver mixture through a coarse sieve, rubbing with a pestle or the back of a spoon into crock or dish. (There will be a good amount of membrane from liver and fiber from onion to discard.) Stir in remaining cream.

Heat oven to 350 degrees. Put crock or dish in a slightly larger pan. Add boiling water to come about halfway up the outside. Bake until a knife inserted in center of pate comes out clean, 45 minutes to 1 1/4 hours. Time will vary according to shape and thickness of cooking vessel. Let cool. Refrigerate. Serve on a tray with French bread and cherry tomatoes. UNCLE FRED'S TOMATO SALAD (6 to 8 servings) 6 large tomatoes 1 small Bermuda onion 3 cloves garlic Salt and pepper to taste 1 teaspoon oregano 6 tablespoons olive oil 1 1/2 teaspoons red wine vinegar

Cut tomatoes into fairly thick slices. Arrange on platter. Cut onion and garlic into very thin slices and strew over tomatoes. Season with salt, pepper, and oregano. Drizzle olive oil and vinegar over tomatoes. Let stand at room temperature for about 1 hour before serving. FLAVIA STUTZ'S SPINACH SALAD (6 to 8 servings) 1 pound fresh spinach (about 1 1/2 bags, 10 ounces each) 1 bunch scallions, thinly sliced 6 strips bacon, cooked and crumbled 1/4 pound mushrooms 6 tablespoons olive oil 2 tablespoons fresh lemon juice 3/4 teaspoon salt 1/8 teaspoon pepper 2 cloves garlic, pressed 1/4 teaspoon dry mustard 1/2 teaspoon sugar 1 egg yolk

Rinse and dry spinach. Tear off and discard tough stems.Rip leaves into bite size pieces. Put in salad bowl. Add scallions and bacon. Slice and add mushrooms as close to serving time as possible.

Mix olive oil, lemon juice, salt, pepper, garlic, mustard, sugar and egg yolk together to make dressing. Just before serving, pour over salad and toss. SPECIAL CHEESE CAKE (8 to 10 servings) 6 tablespoons butter 3 large shredded-wheat biscuits 1/3 cup plain toasted wheat germ 1/3 cup plus 1/2 cup sugar 3 packets (8 ounces each) cream cheese at room temperature 4 eggs 2 teaspoons vanilla

Melt butter in large saucepan. Let cool slightly. Put shredded-wheat biscuits in food processor and work until they are the consistency of fine crumbs. Add wheat germ and 1/3 cup of the sugar. Mix with butter in saucepan. Reserve about 2 tablespoons of the mixture for a topping. Press on bottom of a 10-inch spring form pan. Wipe out food processor.

Put cream cheese, remaining 1/2 cup of sugar and eggs in food processor and work until smooth. Add vanilla. Spread over crust in pan. Sprinkle with reserved crumbs.

Heat oven to 350 degrees. Bake until filling is set, about 30 minutes. Let cool. Refrigerate until firm, about 4 hours. PAT DUBIN'S COLD LIME SOUFFLE (8 servings) 1 envelope plain gelatin 1/4 cup cold water 4 egg yolks 1/2 cup fresh lime juice (about 6 limes) 1 cup sugar 1/2 teaspoon salt 6 egg whites 1 cup (1/2 pint) heavy cream 1/3 cup shredded coconut

Sprinkle gelatin over water and let stand until soft, about 5 minutes. Put egg yolks, lime juice and 1/2 cup of the sugar in top of double boiler. Cook over simmering water, stirring constantly, until somewhat thick, about 7 minutes. Remove from heat. Add softened gelatin and stir until completely dissolved.

Beat egg whites until they hold soft peaks. Add remaining 1/2 cup of sugar gradually, beating until egg whites hold stiff peaks.

Without washing beaters but in a separate bowl, beat cream until it holds soft peaks. First fold egg whites and then fold cream into lime juice mixture. Spoon into plastic drinking cups or other suitable glasses. Refrigerate until firm, about 2 hours.

Toast coconut by cooking in a heavy skillet over moderately low heat. Stir constantly until brown. Let cool. Sprinkle over souffles.