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
Prismatic Curved Diamond Pattern No Background
Source GDJ
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Psychedelic Geometric Background No Black
Source GDJ
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
This is a hot one. Small, sharp and unique.
Source GraphicsWall
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A seamless pattern formed from miutopia's cakes on a tablecloth.
Source Firkin