How to make a Homemade Neck warmer:
Make a large C to fit around your neck. May make wide enough to extend to your shoulders. Use muslin or flannel and make a double C, leaving the middle opening for filling. If making a large one, stitch fabric into sections, leaving open in the middle to be able to fill.
Fill with desired substance, dried cherry pits are great. Sew closed, then cover with a pretty fabric that you like. To do that and make the cover washable: Make a tube the size of the C, allowing for seams and the filled pad. If too large, just seam and make smaller. This tube, larger than the pad will have each end open. After slipping over pad, use pretty ribbon, etc to ties closed on both ends. For maintenance and a clean cover, remove ties, wash, dry and reuse. Don't wash the pad unless you use a substance that can be microwaved, plastic pellets melt.