Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
One more sharp little tile for you. Subtle circles this time.
Source Blunia
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Prismatic Curved Diamond Pattern 6 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
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
This is the remix of "polka dot seamless pattern".The image depicts polka dot seamless pattern.
Source Yamachem
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
A comeback for you: the popular Escheresque, now in black.
Source Patten
An alternative colour scheme to the original seamless pattern.
Source Firkin