A poor, honest shoemaker leaves his last leather cut on the table that evening. The next morning he finds a flawless pair of shoes. The buyer pays more than usual for them. So he can now buy leather for two pairs, and this continues until he is wealthy. Then he and his wife stay up one night and see two small, naked men making the shoes. At his wife's idea, the next time they lay out clothes and shoes for the elves. They put them on and sing "Aren't we boys smooth and fine? Why should we be shoemakers any longer?" Then they dance out and don't come back. The shoemaker is happy for life.
A poor, hardworking maid finds a written invitation from elves to be her godmother. At her master's persuasion, she goes with three elves into a hollow mountain where everything is small and splendid. At her request, she stays happy for three days and leaves with her pockets full of gold. At home, the master has already died, because it was seven years.
A mother's newborn child was swapped by elves for a changeling with a thick head and staring eyes who only eats and drinks. On the advice of her neighbor, she puts him on the stove and boils water in two eggshells to make him laugh. Then he says: "Now I am as old / as the Westerwald, / and have never seen anyone cook in bowls." And laughs, whereupon elves bring back the right child.
Source: Wikipedia