The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Gold Triangular Seamless Pattern No Background
Source GDJ
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
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
Retro Circles Background 7 No Black
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Green Web Background, Seamless tile.
Source V. Hartikainen
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin