Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
A white version of the very popular linen pattern.
Source Ant Ekşiler
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
A free seamless background pattern for use on websites.
Source V. Hartikainen
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
A cute x, if you need that sort of thing.
Source Juan Scrocchi
The classic notebook paper with horizontal stripes.
Source Are Sundnes
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso