I found the idea for this baby blanket in this book. There is a template for the scallops (showing a corner and 2 scallops), but it's a little tricky to construct the whole blanket from the portion given. My blanket isn't precisely square and the scallops are not identical. I was also left with a lot of puckers in all those corners.
I like the clever (to me, anyway) instructions which have you construct the blanket right sides together (with the batting attached to one side) leaving an opening for turning, turn right sides out, press, quilt and topstitch.