In the data sheet:
SiFive FE310-G000 Preliminary Datasheet v1p5
in figure 2.1, on page 3 (labelled, 7 actual), in the top left hand of the diagram, pins 2 and pins 3 are given the same name: QSPI_DQ_2.
Probably, pin 3 should be QSPI_DQ_1 and pin 4 should be QSPI_DQ_0.
cheers,
~adrian