This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
This texture looks like old leather. It should look great as a background on web pages.
Source V. Hartikainen
Seamless Prismatic Geometric Pattern With Background
Source GDJ
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Alternative colour scheme. 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
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A pattern derived from part of a fractal rendering in Paint.net.
Source Firkin
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Inspired by an image that was uploaded to Pixabay by geralt
Source Firkin
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin