Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Classic vertical lines, in all its subtlety.
Source Cody L
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
Prismatic Polka Dots Mark II 2 No Background
Source GDJ
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
Black And White Floral Pattern Background from PDP.
Source GDJ
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
Prismatic Polka Dots Mark II No Background
Source GDJ
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Prismatic Hypnotic Pattern No Background
Source GDJ