As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
A seamlessly tileable pink background texture.
Source V. Hartikainen
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Seamless pattern formed from a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen