Here’s a couple more resources useful for making texture material presets. Commercial projects allowed, though not via “as is” redistribution. Click on the preview images to go to the download pages.
There are separate downloads for the raw leather scanned textures and the seamless tiles.
Also includes brown/tan khaki tiles and herringbone-like tile in addition to the denim ones. It would be easy to recolor the tan texture to an olive drab for a military-style texture.