You won't find ND cotton fabric anywhere. ND tightly controls how fabric with their trademark is used. Twenty years ago I bought some with the leprechaun on it at a local shop and was making schrunchies for a campus fundraiser. They found out about it, rushed over to the fabric store, pulled the fabric off the shelf and threatened to sue both the store and me. DO NOT appliqué or in any other manner produce their icons. If they find out about it they will confiscate it and sue you for copyright and trademark infringement. I am not joking. The cause for which you are making the project makes no difference to them. If you use their icons (including the phrase "fighting Irish") they will come after you. They are even suing Catholic schools that use "Fighting Irish" as their mascots, including the Indianapolis school that actually created the name and gave it to ND.