A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A new one called white wall, not by me this time.
Source Yuji Honzawa
Background formed from the original with an emboss effect
Source GDJ
An alternative colour scheme to the original seamless pattern.
Source Firkin
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Prismatic Abstract Geometric Background 4
Source GDJ
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
A seamless texture of a rough concrete surface.
Source V. Hartikainen
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg