A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Prismatic Abstract Geometric Background 2
Source GDJ
This one has rusty dark brown texture.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
The image depicts a seamless pattern made using a bird's face.
Source Yamachem