Seamless Cardboard Texture #1212
Cardboard CC BY-SA 3.0A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
More Textures
Repeating Stone-Like Background (Dark Brown) #1056
Stone CC BY-SA 3.0A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
Dark Stripes #39
Dark CC BY-SA 3.0Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Background pattern 227 (colour 6) #2309
Red CC 0A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Squares #302
Dark CC BY-SA 3.0Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Background pattern green #1944
Green CC 0To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Fabric of Squares@2X #1096
Light CC BY-SA 3.0As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Seamless Gray Stone Background #1028
Stone CC BY-SA 3.0This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
"Colorful Stripes", Diagonally Striped Background #903
Stripes CC BY-SA 3.0This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Concrete Wall 3@2X #94
Light CC BY-SA 3.0All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Background pattern 315 (colour 5) #1841
Yellow CC 0The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background pattern 234 #2259
Brown CC 0Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Decorative divider 274 #1922
Dark CC 0Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
Background pattern 246 #2186
Red CC 0This was formed by distorting an image of a background on Pixabay.
Source Firkin