Had just enough time today to try this fantasy of mine.
First I rubbed some bananas into my clean hair. They weren't giving me quite enough to work with so I added a layer of instant mashed potatoes and worked the mush in nicely. On top of this, I added patted on some oats and dirt for that nice matted texture that I love.
After I had a nice thick mop started it was time to add the compost materials. Two cups of leftover spinach first and then a tub of uneaten salad from a few days ago. Then a bunch of banana peels piled on top and rubbed in over and over again.
Absolutely driving myself wild with how ruined my hair looked. Will collect more vegetable scraps next time, those were the best. I think some used coffee filters and tea bags might look nice. Still haven't had time to really make a big mess, looking forward to really getting my hair engulfed even more.