Black brick wall pattern. Brick your site up!
Source Alex Parker
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by TheDigitalArtist
Source Firkin
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
Embossed lines and squares with subtle highlights.
Source Alex Parker
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
A seamlessly tileable pink background texture.
Source V. Hartikainen
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A seamless paper background texture colored in pale yellow. This seamless texture is ideal for those who need a yellow background image for their website. The texture resembles paper.
Source V. Hartikainen
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo