There are two sizes in the pattern:
-Small, which makes a wreath approximately 14 inches in diameter
-Large, which makes a wreath approximately 18 inches in diameter

I typically use the merino jumbo yarn from World of Wool, but any wool roving from another supplier (or even a farm!) should work. World of Wool is in the UK, but ships quickly. They sell wool by the kg, so you have to order at least 2 pounds at a time. That should be plenty for the large size and maybe even multiple wreaths.

I sell a kit for this in my Etsy shop as well.

You can also substitute another jumbo-sized yarn or acrylic yarn that is similar to wool roving. You may need additional yardage, as your stitches will probably not be as huge. But the technique is the same.

Many people have added other decorations to their wreaths: felt flowers, ribbon, Christmas or other holiday decor, etc.