Patrice, while your post is now an old one, I do have a suggestion. A friend gave me a gallon of Simple Green. It is wonderful stuff. It cleans up white socks and takes stains out of everything. A friend told me that after Thanksgiving, she had crayon marks on her carpet (ala grandchildren) and wine stains on her linen. She had heard me tell about Simple Green, so she bought some. She was amazed that it was such a fabulous product. It should easily remove pencil markings.
SAM's is one good source. Otherwise, buy it in the automotive dept. Don't ask why.....people use it to get the road grease off their cars. So why not in the laundry. I have not found it to harm any fabrics.
We goota get rid of those marks.
June