Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
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
An alternative colour scheme for the original background.
Source Firkin
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
This was formed by distorting an image of a background on Pixabay.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin