Pattern? Not really.
On every row, I slipped the first stitch purlwise, passed the yarn back between the needle tips and knitted across, including the last stitch. Additional squares were worked by picking up stitches through the back loop of the chain-selvedge.

I used an even number of stitches on each square, worked a double-decrease at the center of alternate rows.

It began with the hole in the centre. I worked a connected-as-you-go ring of smaller mitred squares around it. It just needed to be big enough to go over my head. Once it was done, I came back to the center and added either a few crocheted rounds or an applied i-cord (I don’t really remember) to snug the opening up to head-size.

Thereafter, I just worked rounds of larger or smaller mitred squares until I’d about run out of yarn.