Where can I buy a plain white cotton blanket to print on?

I'm an artist and I do a lot of woodblock printing, I'd like to buy a plain white blanket to print on and then give it as a gift. I don't have the skill to make the blanket from scratch, and I've looked online but everything is quilted or patterned in some way. Does anyone know where I could find one online without this? Thank you! :)