A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Prismatic Polyskelion Pattern No Background
Source GDJ
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Inspired by a drawing in 'Poems', James Smith, 1881.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen