Prismatic Groovy Concentric Background 4 No Black
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
Colour version of the original seamless pattern.
Source Firkin
Retro Circles Background 8 No Black
Source GDJ
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
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
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Prismatic Geometric Pattern Background No Black
Source GDJ
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady