I usually give my mom a bouquet of flowers and take her out for lunch or dinner on Mother's Day. One occasion I remember particularly well is when a few years ago we took a trip to a place just south of Bonn, where there is a museum and, right below, the place's former train station has been transformed into a restaurant. It was a gloriously sunny day in May, and we very much enjoyed our food and the views of the Rhine Valley.
The museum (designed by the same architect as the Getty in Los Angeles, Richard Meier) and the train-station-turned-restaurant
The view from our table on the restaurant's terrace
Lunch -- asparagus, as matching the season
... and that year's bouquet
(as always, with hand-picked flowers, not prebound at the store)