I'm really paranoid about what I put in my hair, but France Luxes has some tiny tige boule barrettes that are very gentle on hair and work really well for what you want. They won't hold a whole lot of hair, but I find this actually works better, because they don't mess up curl pattern. They only come in colors, but they're pretty subtle.
France Luxe Mini Volume Tige Boule - Barrettes - France Luxe Accessories
Former longhair, now CG, living in N. California where the fog meets the wind
3a/b, fine, normal porosity/elasticity, high density
Conditioner wash and style, sometimes with a dab of BRHG.