The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
A bit strange this one, but nice at the same time.
Source Diogo Silva
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Alternative colour scheme. 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
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
White handmade paper pattern with small bumps.
Source Marquis
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Remixed from a drawing in 'An Index to Deering's Nottinghamia Vetus et Nova', Rupert Chicken, 1899. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin