White Kale Leaves
Thank you for contacting Delaware Cooperative Extension. Without seeing an actual sample, it is difficult to tell for sure. However, this does not look like a disease or insect problem to me. It might be frost damage, in which case the new growth should begin to come out normally. It may be that the plants got a touch of herbicide drift from lawn chemicals that may have been applied. Regardless, I would recommend that you monitor the plants and harvest and eat the new growth if it comes out normally.
Kale is one of my favorites! Enjoy!