This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Polyskelion Pattern No Background
Source GDJ
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
This one has rusty dark brown texture.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
A classic dark tile for a bit of vintage darkness.
Source Listvetra
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A background pattern with green vertical stripes. A new striped background pattern. This time a green one.
Source V. Hartikainen
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
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
More in the paper realm, this time with fibers.
Source Jorge Fuentes