UPDATE I have a new version, Mitered Granny Square which includes a diagram that you may want to check out. To help understand how to do the Mitered Granny Square, here is a diagram.
Mitered granny square, free pattern - with photo tutorial & pattern diagram
Amazing step-by-step video tutorial for those who want to learn how to crochet the block stitch and crochet a block stitch baby blanket during the process.
Beautiful crochet mandala pattern This would make a great trivet! Just use a thicker yarn.