A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. A version of the original with random colors.
Source Firkin
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso