Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A free seamless background with pink spots.
Source V. Hartikainen
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Prismatic Groovy Concentric Background 3
Source GDJ
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
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
An abstract web texture of a polished blue stone (or does it look more like ice).
Source V. Hartikainen
A new one called white wall, not by me this time.
Source Yuji Honzawa
A seamless texture of worn out "cardboard".
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin