The data can be obtained through the UCSC Table browser or their downloads area. Either can be imported into Galaxy. There are other sources, but this will ensure that the data is a match for UCSC reference genomes included at http://usegalaxy.org.
To extract the data for human hg38 from the Table browser directly into your Galaxy history, use the left tool panel's Get Data: UCSC Main function, then set up the form like the graphic below (change the genome build, region, and other options as desired and see the User Guide for full usage directions including the dbSNP project's build information):
Thanks, Jen, Galaxy team