A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
Lovely pattern with splattered vintage speckles.
Source David Pomfret
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Same classic 45-degree pattern, dark version.
Source Luke McDonald
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Prismatic Triangular Background Design Mark II 5
Source GDJ
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin