det-any ideas for simple gifts? cards seem a bit wasteful
chocolates/flowers (i think you know that already, lol)
if she has any hobbies you know anything about, get her something for it? doesn't have to be big, she'll appreciate that you take interest in the things she likes.
you could also ask your dad or someone close to her if there is anything that she has been complaining about around the house albeit like an appliance and you could maybe buy her a new one of that.
just spitballing ideas, hope you fellas have a good mothers day =D