A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
A seamless web texture of "green stone".
Source V. Hartikainen
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A repeating gloomy background image. This one consists of a pattern of black chains layered on top of a dark textured background.
Source V. Hartikainen
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
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Continuing the geometric trend, here is one more.
Source Mike Warner
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso