old t-shirts, old white cotton socks with holes in them, go to garage sales and look for white cotten bed sheets, the salvation thrift stores, sell cotton sweatshirts for a quarter, they sell old cotton bedding, Wal Mart sells a bag of all size patches (actually nothing more then a bag of cotton rag cuttings from a t shirt factory some of them appear to be) they claim there is 200 in there but when you cut most of the patches two or three times for a patch to fit, you get a lot more, those sell for a $1.99.