I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
The starting point for this was a texture drawn with the 'Radial Colors' plug-in in Paint.net.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
Prismatic Groovy Concentric Background
Source GDJ
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
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
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin