Free tutorial & video on Crafting Happiness
https://craftinghappiness.com/crochet-spades-stitch-border

You can make this border on any edge, from square to round. It suits any project you might want to embellish with this textured edge pattern.

I recommend you crochet a base row on your edge before starting the border. Use any plain stitch for your base row, I always make a single crochet row around my blankets before crocheting any border.