Shallow soil characteristics were mapped near Shellmound, Mississippi, using the DualEM 421 electromagnetic sensor in October 2018. Data were acquired by towing the DualEM sensor on a wheeled cart behind an all-terrain vehicle (ATV), with the sensor at a height of 0.432 meters (m) above the ground surface. Approximately 175 line-kilometers of data were acquired over an area of nearly four square-kilometers, with 25 m separation between survey lines. Data were manually edited for noise sources such as powerlines or other buried structures and averaged to regular output soundings every 5 m along survey lines. The processed data were inverted to recover models of electrical resistivity structure as a function of depth at each sounding location using a spatially constrained inversion. This data release contains the raw and processed data, as well as inverted resistivity models. Model results show typical depth of investigation from about 4 - 6 m, with spatial variability in mapped electrical resistivity characteristic of fluvial deposition of sediments in channels and scroll bar features adjacent to the Tallahatchie River and nearby abandoned meander channels.