This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Basic Pattern 2 No Background
Source GDJ
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
A seamless texture of black leather. I think it will look best when used in headers, footers or sidebars.
Source V. Hartikainen
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
A version without colours blended together to give a different look.
Source Firkin
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Prismatic Basic Pattern 2 No Background
Source GDJ
Prismatic Geometric Pattern Background
Source GDJ
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
From an image on opengameart.org shared by rubberduck.
Source Firkin