Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
A chequerboard pattern with a fruit theme. The fruits are from a posting by inkscapeforum.it.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
The image is a design of blue glass.How about using it as background image?
Source Yamachem
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen