You could generate such a dataset using Python. A simple approach would be to generate a set of (x, y) coordinates, partition the set, then assign a distinct value for the z coordinate for each partition. An example with 100 points divided into 5 linearly separable partitions:
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
This is not an answer.
If you visit https://sdmdataaccess.sc.egov.usda.gov/QueryHelp.aspx and download the "Table Column Descriptions Report (741K)" PDF, you will get a list of all tables (and column names) for your data.
You can then go to https://sdmdataaccess.sc.egov.usda.gov/Query.aspx and make queries like SELECT * FROM chaashto. You will have to ...