In the summer of 1967, the USAF was conducting a captive carry flight of the Lockheed D-21 reconnaissance drone over Nevada when a damaged attachment bolt in the B-52's pylon that held the D-21 sheared, resulting in the drone and its booster rocket dropping away. The automatic start sequence of the D-21 began and the booster rocket ignited, accelerating the D-21 away. Since the inertial navigation system hadn't been programmed, the D-21 flew unguided until it crashed in the Railroad Valley outside of Area 51.
A local rancher and his wife came upon the scene and took several pictures. Once the Air Force had arrived on scene, as much of the still top secret drone's wreckage was collected and spirited off back to Area 51. The USAF/CIA officer in charge of the clean up, Col. Frank Hartley, found out about the rancher's pictures and not wanting to intimidate the rancher into giving up the photos, he instead asked him if there was anything he wanted in exchange for the film. The rancher told Hartley he had a "hankering" for some cream pie. Hartley made some phone calls to Area 51 and soon a helicopter arrived with a fresh cream pie and Col. Hartley got the film in exchange.
Source: X-Plane Crashes: Exploring Experimental Rocket Plane, and Spycraft Incidents, Accidents, and Crash Sites by Peter W. Merlin and Tony Moore. Specialty Press, 2008, p99.