A background pattern with blue on white vertical stripes.
Source V. Hartikainen
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
One more sharp little tile for you. Subtle circles this time.
Source Blunia
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Background 2
Source GDJ
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
A bit strange this one, but nice at the same time.
Source Diogo Silva
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Zero CC tileable hard cover cells book texture, 4k, scanned and made by me. CC0
Source Sojan Janso
A comeback for you: the popular Escheresque, now in black.
Source Patten
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
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez