This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
A free background pattern with abstract green tiles.
Source V. Hartikainen
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
A dark striped seamless pattern suitable for use as a background on websites.
Source V. Hartikainen
I’m not going to use the word Retina for all the new patterns, but it just felt right for this one. Huge wood pattern for ya’ll.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Prismatic Abstract Geometric Background 5
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
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