CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Derived from a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
Sharp pixel pattern, just like the good old days.
Source Paridhi
A new one called white wall, not by me this time.
Source Yuji Honzawa
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen