What is the best place too hide a tampon from your mom?

There's absolutely no reason to hide tampons from your mom, just let her see the tampons.

Tampons are not something to be ashamed of so not something to hide from anyone. If she said you couldn't use tampons then simply don't use tampons, hiding the fact you're using tampons from her won't work as she'll realise you're using fewer pads and see used tampons in the bin. Also your mom needs to know you're using tampons as if you contract TSS she needs to know early to get you help.