A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Sometimes you just need the simplest thing.
Source Fabricio
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso
Classic vertical lines, in all its subtlety.
Source Cody L
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Embossed lines and squares with subtle highlights.
Source Alex Parker
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
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
Prismatic Snowflakes Pattern 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 light yellow background pattern consists of an irregular pattern of spots. Here's a light background pattern with yellowish tint.
Source V. Hartikainen
This one needs to be used in small areas; you can see it repeat.
Source Luca
Continuing the geometric trend, here is one more.
Source Mike Warner
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić