This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The image depicts a seamless pattern of a tortoise in tortoiseshell (hexagon).
Source Yamachem
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
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
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee