Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
White circles connecting on a light gray background.
Source Mark Collins
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Pattern formed from simple shapes. Black version.
Source Firkin
Fix and cc0 to get the tile this is based on.
Source SliverKnight
You guessed it – looks a bit like cloth.
Source Peax Webdesign
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
A colourful background drawn originally in paint.net and vectorised in Vector Magic.
Source Firkin
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Might not be super subtle, but quite original in its form.
Source Alex Smith
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle