Here is a set I made with a 1/2" child size headband and an 18" doll headband. These are fun gift ideas so your little girl had a matching headband for her favorite doll. The larger child sized headband is made with 3/8" grosgrain and the doll sized headband is made with 1/4" grosgrain.
Here is an American Girl doll that belongs to my other niece modeling a doll sized headband. (Sorry, I couldn't seem to get my niece and the doll at my house at the same time for a photo of both of them together.)
Below are some additional headband samples. You can make so many variations just by varying the starting ribbon positions or using printed ribbon. A headband woven with just one color ribbon is also very nice.
The white headband below is made with 3/8" white satin with grosgrain edge ribbon and would be lovely for a 1st communion or even a flower girl at a wedding.
This final headband is a 1/4" headband and I used 1/4" grosgrain ribbon. I love the smaller profile of this width of headband.