White Paperboard@2X #375
 Fabric  CC BY-SA 3.0

Could be paper, could be a Polaroid frame – up to you!

Source Chaos

 More Textures
Background pattern 5 #224
 Noise  CC 0

A pattern drawn in Paint.net and vectorized in Inkscape.

Source Firkin

Dark Brick Wall@2X #136
 Wall  CC BY-SA 3.0

Black brick wall pattern. Brick your site up!

Source Alex Parker

Prismatic Groovy Concentric Background #449
 Noise  CC 0

Prismatic Groovy Concentric Background

Source GDJ

Decorative divider 219 #2231
 Dark  CC 0

Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.

Source Firkin

Rubber Grip #101
 Dark  CC BY-SA 3.0

A very slick dark rubber grip pattern, sort of like the grip on a camera.

Source Sinisha

Colorful Floral Background #479
 Noise  CC 0

Colorful Floral Background

Source GDJ

Background pattern 235 #2255
 Yellow  CC 0

To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Prismatic Snowflakes Pattern 2 No Background #412
 Light  CC 0

Prismatic Snowflakes Pattern 2 No Background

Source GDJ

Mosaic Gems Background #526
 Noise  CC 0

Mosaic Gems Background

Source GDJ

Concrete Wall 2 #79
 Wall  CC BY-SA 3.0

A light gray wall or floor (you decide) of concrete.

Source Atle Mo

Prismatic Abstract Geometric Background 3 #270
 Noise  CC BY-SA 3.0

Prismatic Abstract Geometric Background 3

Source GDJ

Background pattern 6 #225
 Noise  CC 0

Another fairly simple design drawn in Paint.net and vectorized in Inkscape.

Source Firkin

Colorful Floral Background No Black #481
 Light  CC 0

Colorful Floral Background No Black

Source GDJ

Background2@2X #477
 Wall  CC 0

rug texture background

Source Jilllio

Zig-zag pattern 5 #2414
 Grid  CC 0

A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.

Source Firkin