If i was in that position I would try to make a nice dinner and if i would give a gift it would be something unexpected and unconventional. Last gift i gave was a handful of whole walnuts(we both dont have a nutcracker). You could do the “forgot this one thing” but start with something cheap and unexpected, something what makes her laugh and also think “why the hell would give this to me”
If you want to marry you could do the same but start with a particularly nice looking pebble
Greg