Here is the link to the patterns that EGF has had success with. Particularly, Toni's Burial Gown as is for a girl and DC the skirt for a boy. Sharon, one of our wonderful volunteers, has emailed me directions for making it larger. I can share that with those that want it.
As you will look, you will notice that a few of the links are no good. Here are the corrections:
Marilyn's Bubble Suit and Aunt B's Angel Wrap
I know nothing about knitting, but this Sleeper Sack is really popular. It is, however, small. Since I know nothing about knitting, it may easily be enlarged.
You can also look through Bev's Country Cottage and pick one that suits your ability. Kathy has some personal crochet patterns on her sidebar, too. Wool Winder does a great job of detailing the patterns she uses, too.