You may use it as is, or modify it as you like.
Source V. Hartikainen
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamlessly tileable pink background texture.
Source V. Hartikainen
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
Almost like little fish shells, or dragon skin.
Source Graphiste
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The classic notebook paper with horizontal stripes.
Source Are Sundnes
Prismatic Floral Background No Black
Source GDJ
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen