The image depicts polka dot seamless pattern.
Source Yamachem
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
Zero CC tileable Laminate wood texture, photographed and made by me. CC0
Source Sojan Janso
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac