Scott K. Williams, collector of vast quantities of historical information about St. Louis on his "History's Time Portal to Old St. Louis", devotes a page to clay (and coal) mining and brick production (with some photos of bricks) that occurred in St. Louis between the Civil War and the 1st World War, here:
The list was compiled from a map by Mimi Garstand, and published in 1987 by the Missouri Dept. of Natural Resources, Division of Geology and Land Survey, Rolla, MO.
After you get to this page, and if you want to learn more, much more, about St. Louis, remove "underground" from the address and click again to reach Mr. Williams' top page, opening the door to an amazing collection of photos, post cards and records, and including the music and words to "Under the Anheuser Bush".
bricks, clay mine, Missouri, Scott K. Williams, St. Louis,