My mom would probably think they were really cool, but I would feel really awkward! If I really wanted to get her something like that, I would get her a gift card to EF, put together a wish list of suggestions for her, and let her pick something herself.
It would be no more awkward than going lingerie shopping with her before her (recent) wedding, and useful, and if she doesn't like them I can't imagine her asking me for a mother's day present again, so why not? XD
Absolutely no way my Mum would die of embarrassment; she never even explained periods to me as a kid, I thought I was dying when I first came on.
But I'm alot older than some of you and my Mum is nearly in her 80's, but even if she was younger it would be a no as she came from a different generation to who we all are now.
Im so pleased people talk about this stuff now!