Republican Massachusetts Sen. Scott Brown hasn't let all the back-slapping and headlines go to his head. First, we learn that he drove his green pickup truck to Washington, where he parks it across the street from the U.S. Capitol. And then there's the duffle bag he carries with him. Inside are hundreds of letters from constituents congratulating him on winning the seat previously held by Edward M. Kennedy. Some tell stories about meeting Brown on the campaign trail. Others share long-ago recollections of the senator, like the copy of a 1972 newspaper clipping about Brown's play in a little league game that a fan included in a letter. He reads each one, then scribbles a reminder to "write back" on the ones that he wants to answer. For those, says an aide, "he writes a very personal note back."