This is an easy pattern. Circles are easy to crochet in general in simple dc, sc, etc.: just keep increasing groupings one more stitch farther apart for each and every new row and the circle should lay flat even if you keep going like that for forever.
Recycled jeans notebook or planner. Use a regular notebook, and cut up them jeans that the kids have outgrown. Also a good idea: using a larger notebook and a patch/screenprint from an old favorite shirt.