  We report on experiments of many small motors -- cell phone vibrators --
glued to and interacting through a resonant plate. We find that individual
motors interacting with the plate demonstrate hysteresis in their steady-state
frequency due to interactions with plate resonances. For multiple motors
running simultaneously, the degree of synchronization between motors increases
when the motors' frequencies are near a resonance of the plate, and the
frequency at which the motors synchronize shows a history dependence.
