A quick search of the web will yield many source for GIS data. Most will produce online maps that are useless as GIS data and not downloadable. Take care to download formats compatible with the software you are using (Shape files for vector data and GeoTIF for raster).
Sites where I have found useful data
https://gdg.sc.egov.usda.gov/ Climate Data
https://www.usgs.gov/the-national-map-data-delivery/gis-data-download General Data
https://earthexplorer.usgs.gov/ Imagery