A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A seamless pattern formed from background pattern 102
Source Firkin
A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.
Source V. Hartikainen
Colour version of the original pattern.
Source Firkin
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
From a drawing in 'Prose and Verse ', William Linton, 1836.
Source Firkin
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Colorful Floral Background No Black
Source GDJ
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen