CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
A bit strange this one, but nice at the same time.
Source Diogo Silva
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
Continuing the geometric trend, here is one more.
Source Mike Warner
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
A free background tile with a pattern of pink bump dots. This background tile is sweet! Moreover, it's designed for use as website backgrounds.
Source V. Hartikainen
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
An attempt for cleaning up the original image in a few steps.
Source Lazur URH