I guess the next question is, any particular colors you do/do not want? I do have something of a preponderance of dark colors, but there are bound to be a few brighter things lurking in the boxes. And how big do your fabric squares need to be?

(What I might just do is just put together one quickie envelope of really tiny scraps of known fiber content that you can practice burn testing on, since those can be all the odds and ends too small to do anything else with. And then I can try to put together a slightly bigger batch of actual usable scraps. Hmmm, I should dig through the button stash, too...I bet there's some unwanted pastels that came in grab bags I could throw in while I'm at it...)