Popcorn--perhaps the oldest form of ""our wonderful gift from the Indians""--can be grown in your own backyard, bought in almost any American supermarket, cooked (young readers are reminded) without an electric popper, and, says Williams, enjoyed through the year in a seemingly endless variety of forms. Ma Goodness! Williams serves it with chocolate fondue in January, on a cardboard log cabin for Lincoln's birthday, with maraschino cherries and marshmallows (God help us) for Washington's, with lime jello for St. Patrick's and parmesan cheese for Columbus Day. . . and so on up to the inevitable gunked up Christmas confections and decorations. There's even a lo-cal popcorn made with low-calorie salad dressing, though syrup coating is far more common here. All in all, this is just one more sad example of what we've done with all those wonderful gifts from the Indians.