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
3a/b, F, normal porosity

Wash with either Suave Tropical Coconut, As I Am, or CJ Daily Fix
Condition with STC or Yes to Blueberries and detangle with Denman, rinse very lightly (baptismal rinse)
Add LAL gel, either Sport or Wet Look, scrunch with flour sack towel, and plop
Diffuse 5 minutes, then air dry