The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Original minus the background
Source Firkin
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Feel free to download this "Dark Wood" background texture for your web site. The background tiles seamlessly!
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Looks like an old rug or a computer chip.
Source Patutin Sergey
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
This seamless web background texture looks like gray stone. It's great for using as a background image on web pages, or on some of their elements. Anyway, I hope you will find use for it.
Source V. Hartikainen
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