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

Nice and simple crossed lines in dark gray tones.

Source Stefan Aleksić

 More Textures
Carbon Fiber@2X #4
 Carbon  CC BY-SA 3.0

A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.

Source Atle Mo

Sine wave background 2 #1734
 Dark  CC 0

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

Source Firkin

Background pattern 259 (colour 3) #2130
 Colorful  CC 0

Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Random Grey Variations@2X #70
 Stripes  CC BY-SA 3.0

Stefan is hard at work, this time with a funky pattern of squares.

Source Stefan Aleksić

Prismatic Abstract Background Design #403
 Noise  CC 0

Prismatic Abstract Background Design

Source GDJ

Prismatic Rounded Squares Grid 3 No Background@2X #490
 Noise  CC 0

Prismatic Rounded Squares Grid 3 No Background

Source GDJ

Seamless Cardboard Texture #1212
 Cardboard  CC BY-SA 3.0

A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.

Source V. Hartikainen

Decorative divider 229 #2151
 Dark  CC 0

From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.

Source Firkin

"Polished Stone", Gray Background Pattern #1053
 Stone  CC BY-SA 3.0

A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).

Source V. Hartikainen

Paper 1 #15
 Paper  CC BY-SA 3.0

A slightly grainy paper pattern with small horizontal and vertical strokes.

Source Atle Mo

Circles@2X #186
 Light  CC BY-SA 3.0

One more sharp little tile for you. Subtle circles this time.

Source Blunia

Background pattern 224 (colour 5) #2338
 Colorful  CC 0

To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.

Source Firkin