A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
A background pattern with a look of rough fabric.
Source V. Hartikainen
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Recreated 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
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
Prismatic Abstract Geometric Background 3
Source GDJ
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
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
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Prismatic Geometric Pattern Background 2
Source GDJ