Clean the fiddleheads by snipping off the tough 1/8-inch at the bottom and any stray coarse tips visible. Wash the ferns in cold water. Bring 2 quarts water to a boil and add a teaspoon salt. Add the fiddleheads to the boiling water, return to the boil and cook for 2 to 3 minutes or just until tender. Drain the boiling water and refresh the ferns in ice water. Drain and pat dry the ferns.
In a large saute pan, heat the butter over medium heat. As the butter begins to bubble, add the dry, blanched fiddleheads and saute for 2 minutes. Add the lemon juice, season with salt and pepper and serve immediately.