Background pattern 19 (outline) #204
Light CC 0A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
More Textures
Wet Paper Background (Pale Yellow) #1224
Yellow CC BY-SA 3.0A seamless paper background colored in pale yellow.
Source V. Hartikainen
Groovepaper #577
Paper CC BY-SA 3.0With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Diamond pattern (colour 8) #2273
Red CC 0From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Batthern #324
Grid CC BY-SA 3.0Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Shattered@2X #952
Gray CC BY-SA 3.0A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
Double Lined #51
Stripes CC BY-SA 3.0Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Wall #1246
Wall CC 0Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
White Plaster #368
Wall CC BY-SA 3.0Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Tessellation 16 #2215
Yellow CC 0The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
"Beige Wall", Tileable Background #1189
Concrete CC BY-SA 3.0This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
Floral background 22 (colour) #1779
Green CC 0From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Tessellation 11 (variant 3) #2536
Grid CC 0The original enhanced with one of Inkscapes's filters.
Source Firkin
Lined Paper@2X #1035
Light CC BY-SA 3.0I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Background pattern 251 (colour 2) #2166
Yellow CC 0To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Colorful Floral Background 3 No Black@2X #486
Light CC 0Colorful Floral Background 3 No Black
Source GDJ
Floral divider 7 #1747
Dark CC 0From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Gold Triangular Seamless Pattern No Background #272
Light CC 0Gold Triangular Seamless Pattern No Background
Source GDJ
Gray Lines #913
Light CC BY-SA 3.0Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Spiral background 2 #2245
Colorful CC 0Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
Dark Grunge Texture (Seamless) #1125
Grunge CC BY-SA 3.0Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
Background pattern 252 (colour) #2161
Colorful CC 0Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark Tile-able Grunge Texture #1123
Grunge CC BY-SA 3.0Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Blizzard #663
Paper CC BY-SA 3.0This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud