A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
This is the remix of "polka dot seamless pattern".The image depicts polka dot seamless pattern.
Source Yamachem
It’s big, it’s gradient—and it’s square.
Source Brankic1979
Sharp pixel pattern, just like the good old days.
Source Paridhi