The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
This background pattern contains a texture of yellow wood planks. I think it looks quite original.
Source V. Hartikainen
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by DavidZydd
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Prismatic Groovy Concentric Background 5
Source GDJ
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo