Background pattern 309 (colour 3) #1864
 Red  CC 0

Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.

Source Firkin

 More Textures
crissXcross@2X #112
 Dark  CC BY-SA 3.0

Dark pattern with some nice diagonal stitched lines crossing over.

Source Ashton

Prismatic Groovy Concentric Background 4 No Black@2X #464
 Noise  CC 0

Prismatic Groovy Concentric Background 4 No Black

Source GDJ

Abstract Tiled Background Extended 8 #519
 Noise  CC 0

Abstract Tiled Background Extended 8

Source GDJ

Diagmonds@2X #337
 Dark  CC BY-SA 3.0

Love the style on this one, very fresh. Diagonal diamond pattern. Get it?

Source INS

Prismatic Floral Background@2X #474
 Dark  CC 0

Prismatic Floral Background

Source GDJ

Background pattern 19 (black) #203
 Dark  CC 0

A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.

Source Firkin

Prismatic Groovy Concentric Background 2 No Black #455
 Noise  CC 0

Prismatic Groovy Concentric Background 2 No Black

Source GDJ

Groovepaper #577
 Paper  CC BY-SA 3.0

With a name like this, it has to be hot. Diagonal lines in light shades.

Source Isaac

Retro Circles Background 6@2X #429
 Noise  CC 0

Retro Circles Background 6

Source GDJ

Tessellation 16 (colour 3) #2213
 Green  CC 0

The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.

Source Firkin