“James W. Pumphrey owned a livery stable on C Street in Washington, D.C., just behind the National Hotel where Booth stayed when he was in town. Booth became a patron of Pumphrey’s, renting horses from him on several occasions, including the night of the assassination. Booth stopped by Pumphrey’s stable shortly after noon on April 14th, asking to reserve a particularly horse, and to have it ready at 4 o’clock that afternoon. When Booth stopped by the livery the horse had already been rented to somone else and Booth had to settle for a bay mare.” – Steers, Assassination Encylopedia
Congressional Cemetery has a wonderful news article about James Pumphrey trying to cheat the gas company in 1883 (bottom of page 5).