Give her something you gave her a long time ago. Something from before you were married would be speciality good. The gift is not as important as the memories it will bring back, so choose wisely.
Or – give her something to remind her of a place you used to go – a box of straws if you hung out at a malt shop, a menu from the place you used to eat often, a card or soap bar from the hotel were you honeymooned.
By The Way: Such things qualify as romantic!