When she got mad because you wanted to give a nice gift to your aunt, what would happen if you questioned her on her reasoning? “Why shouldn’t I show my love to my aunt who I love with a nice gift, Mom?”

You could try this suggestion of Tisha's, Hvert. It might even get you somewhere if you took the proper plaintive, respectful, questioning tone as if you really wanted to know. (Which actually you do). It might be worth a try.

My late mother often got nasty or dismissive when I spoke to her, so I used to spend hours trying to figure out the proper wording and more importantly the proper tone that might stop her in her tracks and make her turn around and examine herself and actually THINK about the question I was asking her. In other words I was pretty much falling all over myself not to give offense. Occasionally it actually worked. But you'd have to have just the right words, just the right tone.