J.C.
This is what worked for me when this happened. Get some 20 Mule Team Borax from the laundry aisle. Wash the clothes in Hot water with regular detergent and Borax, once the water is in the washer, turn the washer off and let them sit in the hot water and soak for awhile, bit not long enough for the water to get cold, then turn it on again and let the agitator work as usual. Some may come clean the first wash, but you might have to repeat this a couple of times.
To get it out of the dryer we turned the dryer on for a few minutes so the crayon was melted again, and used a rag and most just wiped off, we used a magic eraser for the harder stuff, and then a wet rag towel to a final wipe and see if we missed anything. Than we put wet rags in the dryer and ran the dryer to make sure that no more crayon was in the dryer before we put the clothes in it.