A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Black brick wall pattern. Brick your site up!
Source Alex Parker
Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith