A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Kaleidoscope Prismatic Abstract No Background
Source GDJ
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
You guessed it – looks a bit like cloth.
Source Peax Webdesign
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Pattern produced in Paint.net using the Vibrato plug-in.
Source Firkin
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Geometric Pattern Background No Black
Source GDJ
Just like the black maze, only in light gray. Duh.
Source Peax
A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin