A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
A seamless background of warped stripes on paper.
Source V. Hartikainen
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
Prismatic Groovy Concentric Background
Source GDJ
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
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
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Less Black than we're painted', James Payn, 1884.
Source Firkin
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
This is a remix of "geometrical pattern 01".
Source Yamachem