Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Remixed from a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A colourful background drawn originally in paint.net and vectorised in Vector Magic.
Source Firkin
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo