Suggest having a spa day, and ask if you can style her hair for her. (Rinse it, condition it, put some products in it, etc.)
She may find out that afterwards, not brushing it is a good idea. Or not, but it's worth a chance. Let her know that she can still comb
it or finger comb it (when it's wet), but not brush it.
Some people's curls will tangle up a lot if not cared for correctly (mine did that a lot before I stopped shampooing, and they always looked like a bee-hive). Show her some techniques.
Keep in mind, I'm not encouraging you to decieve your mother or anything, maybe even tell her "hey mom, I love your hair, and i want to try and style it sometime" or whatever you want to say.
P.S. I just looked at your pictures... your hair is so nice, and i loved the blue dress you were wearing. Very cute.
Of course, you're very pretty as well.