Feel free to use this seamless background texture as a background on a web site. It's colored in a light pink color and is seamlessly tile-able.
Source V. Hartikainen
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
Seamless Prismatic Geometric Pattern With Background
Source GDJ
You know you love wood patterns, so here’s one more.
Source Richard Tabor
There are many carbon patterns, but this one is tiny.
Source Designova
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba