Looks like nori seaweed sheets, some herbs including parsley and basil, egg yolks, soybean and grapeseed oils, and cheeses contain K2 as well(in rough order of concentration).

In case anyone isn't sure about kimchi and natto every few days, but "for better cognitive ability" would be a nice excuse usable for occasional sushi rolls, stir-fries, just a bit of extra Parmesan, maybe even fries :p