By popular request, an outline version of the pentagon pattern.
Source Atle Mo
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
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
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
Prismatic Abstract Line Art Pattern Background
Source GDJ
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
From a drawing in 'Kingsdene', Maria Fetherstonehaugh, 1878.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
There are many carbon patterns, but this one is tiny.
Source Designova
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts