F. L. Mundy operated at least two different lumber producing mills in Marion County. One was a sawmill plant located three miles east of Jefferson on the Missouri, Kansas & Texas in 1904. His primary customer was Victoria Lumber Company of Shreveport, which received its shipment from Mundy's Mill over the tracks of the Kansas City Southern. He contracted with Samuel Thompson for supplies. F. L. Mundy mortgaged his mill to Victoria Lumber for $1500 in March 1906. He mortgaged his boiler and engine at the Mundy Mill with A. M. Rhyne in April 1906. Mundy was still selling lumber in November 1906. Victoria Lumber continued to buy Mundy's lumber, which would be loaded at Moorings post on the Kansas City Southern and shipped to Victoria Lumber Company at Shreveport Marion County mill. He is listed as F. L. Monday, manufacturing lumber and shingles at Jefferson, according to the Reference Book of the Lumbermen's Credit Association, January 1905.
The Mundy Shingle Mill was a F. L. Mundy operation. Mundy agreed to make shingles for Torrans Manufacturing Company of Jefferson, Marion County, in 1896. The mill was located on Big Cypress Bayou below the Oil Mill. Equip included steam machinery, a shingle machine, and a drop saw. The Mundy Shingle Company was listed at Jefferson in 1928 in a trade journal. It had a sawmill and cut shingles from a variety of trees.