Dark Denim@2X #30
 Dark  CC BY-SA 3.0

A dark denim looking pattern. 145×145 pixels.

Source Atle Mo

 More Textures
White Texture #131
 Light  CC BY-SA 3.0

Not the most creative name, but it’s a good all-purpose light background.

Source Dmitry

Rice Paper@2X #339
 Paper  CC BY-SA 3.0

Scanned some rice paper and tiled it up for you. Enjoy.

Source Atle Mo

“Transparent” Background Pattern #493
 Light  CC 0

An emulated “transparent” background pattern, like that of all kinds of computer graphics software.

Source AdamStanislav

Diamond pattern (colour 5) #2281
 Red  CC 0

From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Prismatic Floral Background No Black #475
 Light  CC 0

Prismatic Floral Background No Black

Source GDJ

Background pattern 315 (colour 2) #1844
 Red  CC 0

The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Type #276
 Dark  CC BY-SA 3.0

The perfect pattern for all your blogs about type, or type-related matters.

Source Atle Mo

Fancy Deboss@2X #178
 Fabric  CC BY-SA 3.0

Luxury pattern, looking like it came right out of Paris.

Source Daniel Beaton

Spiral pattern 3 #1934
 Dark  CC 0

From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.

Source Firkin

Background pattern 215 (colour 4) #2368
 Green  CC 0

A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.

Source Firkin

Retro Circles Background 5 #424
 Noise  CC 0

Retro Circles Background 5

Source GDJ

Fabric pattern (colour 4) #2399
 Fabric  CC 0

Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin