A heavy hitter at 400x400px, but lovely still.
Source Breezi
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Just like the black maze, only in light gray. Duh.
Source Peax
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Fix and cc0 to get the tile this is based on.
Source SliverKnight
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
The tile for this is based on a repeating unit close to a design on Pixabay. It can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A brown metallic grid pattern layered on top of a dark fabric texture. It should look great when using as a tiled background on web pages, especially blogs.
Source V. Hartikainen
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
The classic notebook paper with horizontal stripes.
Source Are Sundnes