A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
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
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Element of beach pattern with background.
Source Rones
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A free seamless texture of reptile skin colored in a dark brown color. As always, you may use it as a repeated background image in your web design works, or for any other purposes.
Source V. Hartikainen
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin