Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
From a drawing in 'From Snowdon to the Sea. Striking stories of North and South Wales', Marie Trevelyan, 1895.
Source Firkin
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Light and tiny, just the way you like it.
Source Rohit Arun Rao
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Seamless Light Background Texture.
Source V. Hartikainen