The mechanisms underlying the generation of plasma flows play a crucial role to understand transport in magnetically confined plasmas. The amplitude of measured parallel flow is significantly larger than those resulting from simulations. Recent experiments have pointed out the possible influence of turbulence to explain flows in the plasma boundary region. This paper reports the first experimental evidence of significant radial gradients in the cross-correlation between parallel and radial fluctuating velocities near the LCFS in JET tokamak and TJ-II stellarator. These gradients are mainly due to the radial variations in the level of poloidal electric field fluctuations and in the cross-phase coherence. These findings might provide the underlying physics of spontaneous toroidal rotation and large parallel flows in plasma boundary reported in fusion plasmas.