Depends on how "cool" your mom is!
Mine isn't. I have strongly considered buying my mother a "Faith" vibe (the pink ribbon breast cancer one) since her mother had breast cancer and a percentage goes to that cause. That way I can always laugh off what it is if it's awkward and maybe she'd be less embarrassed (ie teasing me) to recieve it, since it's for a good cause.
Maybe Faith would be a good first one for your mum?