That vegetables-in-gelatin thing is Perfection Salad
. It was actually a third-prize winner in a 1905 recipe contest sponsored by the Knox Gelatin company. Fannie Farmer was one of the judges and it was published in the 1906 edition of her cookbook as "Jellied Vegetables."
The link above is a 1915 cookbook published by Knox. in case you can't read the recipe:
1 envelope Knox Sparkling Gelatine,
1 cup cold water.
1 cup mild vinegar.
2 tablespoonfuls lemon juice,
2 cups boiling water.
2 cup sugar.
1 teaspoonful salt.
1 cup cabbage, finely shredded.
2 cups celery, cut in small pieces.
2 pimentoes, cut in small pieces.
Soak gelatine in cold water five minutes. Add vinegar, lemon juice, boiling water, sugar, and salt. Strain, and when mixture begins to stiffen, add remaining ingredients. Turn into mold, first dipped in cold water, and chill. Remove to bed of lettuce or endive. Garnish with mayonnaise dressing, or cut in cubes, and serve in cases made of red or green peppers, or turn into molds lined with canned pimentoes. A delicious accompaniment to cold sliced chicken or veal.