Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
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
A free background pattern with abstract green tiles.
Source V. Hartikainen
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
Prismatic Floral Background No Black
Source GDJ
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
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 seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
You were craving more leather, so I whipped this up by scanning a leather jacket.
Source Atle Mo
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
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
The classic notebook paper with horizontal stripes.
Source Are Sundnes