You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
A bit of scratched up grayness. Always good.
Source Dmitry
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Hypnotic Pattern No Background
Source GDJ
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
More in the paper realm, this time with fibers.
Source Jorge Fuentes
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer