WaveCut #75
 Light  CC BY-SA 3.0

If you like it a bit trippy, this wave pattern might be for you.

Source Ian Soper

 More Textures
Retro Circles Background 6 #428
 Noise  CC 0

Retro Circles Background 6

Source GDJ

Zig Zag #328
 Dark  CC BY-SA 3.0

So tiny, just 7 by 7 pixels – but still so sexy. Ah yes.

Source Dmitriy Prodchenko

Retro Squares Background 2 #416
 Noise  CC 0

Retro Squares Background 2

Source GDJ

Prismatic Dots Background 2 #503
 Noise  CC 0

Prismatic Dots Background 2

Source GDJ

Cross Stripes@2X #48
 Dark  CC BY-SA 3.0

Nice and simple crossed lines in dark gray tones.

Source Stefan Aleksić

Background pattern 272 (colour 2) #2056
 Pink  CC 0

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

Source Firkin

Clover with background #237
 Paper  CC 0

Clover with background for St. Patrick's Day. Add to a card with a doily, ribbon, a leprechaun or other embellishments.

Source BAJ

Grunge Wall #81
 Wall  CC BY-SA 3.0

Light gray grunge wall with a nice texture overlay.

Source Adam Anlauf

Tessellation 15 (colour 2) #2221
 Yellow  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