Emily from Nap Time Creations shares a free pattern for this sweet sleeveless baby romper. The body of the romper is gathered on to a plain yoke, with optional ruffles sewn across. She shows it on her daughter, but this would also be cute for baby boys. The pattern comes in three sizes: 0-3 months, 3-6 months, and 6-9 months. You can get the pattern and tutorial at Nap Time Creations.
[photo from Nap Time Creations]