Last year she got a Mercedes Benz SUV from her boyfriend as a 20th birthday gift.  But yesterday Hilary Duff was spotted keeping things a little more low-key for her big 2-1.

The paparazzi caught up to the “War, Inc.” hottie as she meandered around New York City with beau Mike Comrie, stopping into a children’s bookstore as part of her 21st birthday activities.

Source: http://www.gossipgirls.com