However, here are some options you could use, depending on the context:
Informal:
* A head of hair
* A mane of hair (for long, thick hair)
* A shock of hair (for unruly or wild hair)
* A mop of hair (for thick, unkempt hair)
Figurative:
* A cascade of hair (for flowing, long hair)
* A crown of hair (for beautiful, well-maintained hair)
More poetic:
* A halo of hair
* A tapestry of hair
Ultimately, the best collective noun for hair depends on the specific context and the desired tone of your writing.