A bit strange this one, but nice at the same time.
Source Diogo Silva
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Seamless Green Tile Background
Source V. Hartikainen
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein