Pattern: "Square 40" from 101 Crochet Squares by Jean Leinhauser.
This circle-in-a-square worked up to about 7". I changed colors right after the circle instead of after the next round so that the posts that attach the circle part to the square part would be yellow. The corners of the final round were supposed to be solid dc stitches, but I put a chain space in the middle because it really helps later when I join a bunch of squares together. Also I like pointy corners, and I think that when you don't use a chain space at the corner it becomes too rounded.
I have moved and reorganized about half of my craft stuff, and the half that isn't nice and neat includes my fabric. That's why I'm using modern fabric instead of vintage today. This Heather Ross fabric is one of my favorites!