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
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
From a drawing in 'Royal Ramsgate', James Simson, 1897.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Basic Pattern 2 No Background
Source GDJ
A heavy hitter at 400x400px, but lovely still.
Source Breezi
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
The base gradient edited so now more details are rendered.
Source Lazur URH
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering