A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
This is the remix of an OCAL clipart called "Art Nouveau ornament" uploaded by "microcosme".Thanks.This is a seamless pattern of an Art Nouveau ornament.
Source Yamachem
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
Fix and cc0 to get the tile this is based on.
Source SliverKnight
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Sometimes you just need the simplest thing.
Source Fabricio
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Alternative colour scheme to the original.
Source Firkin
"Beige Stone", Tileable Texture.
Source V. Hartikainen
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
Remixed from a drawing in 'Some account of the Worshipful Company of Ironmongers', John Nicholl, 1866.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a drawing in 'Incidents on a Journey through Nubia to Darfoor', F. Ensor, 1891.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin