Joseph Luft's Philatelic Resources on the Web is an annotated directory of Web resources of interest to stamp and coin collectors. You may find an old copy of the original Action Comics Superman, a very highly valued item. It includes articles on how to collect comic art, where and how to find it and why you should want to collect comic art in the first place. Certain kinds of antique wooden farm buckets are worth money, especially those carved out by hand from a tree section or made of wooden rails or slats held together by metal hoops can bring a good price. In fact, just about any early Mickey Mouse product will be valuable.
Books are probably offer the best opportunity for junkyard and attic finds.
Book rarities don't look like anything special, so they can easily be overlooked. A hidden goldmine, for sure. And dolls are more than attractive heirlooms, they're valuable. What used to be art for the poor could be worth something now. Batches of old papers sometimes contain celebrity autographs.