CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
You know you love wood patterns, so here’s one more.
Source Richard Tabor
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Seamless pattern formed from a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
Prismatic Hexagonalist Pattern No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen