This one is amazing, truly original. Go use it!
Source Viahorizon
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Element of beach pattern with background.
Source Rones
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
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
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
The image depicts a seamless pattern of a fishnet with a plenty of fish.It may be a lucky charm for fishermen.
Source Yamachem
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
Prismatic Geometric Pattern Background 2
Source GDJ
Pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
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
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
This is sort of fresh, but still feels a bit old school.
Source Martuchox