Our practice run: some were more successful than others! We found that if we used the sledge hammer on a hard surface and hit about five times for each letter, we got the best impression. Our best hard surface was the concrete patio.
Eventually we made plant stakes from old silverware: sage, radish, oregano, and thyme on the forks, and basil, lavender, and strawberries on the spoons.
We flattened the spoons and forks by pounding hard on one side and then the other until they flattened out nicely.