These 5 TPB are from an interesting set, written for students, but instructive to all of us. The books approach their subject by introducing first the primary sources, and then interpretations by expert authorities. When I was in school we never were exposed to primary sources, so this sounds like a fascinating idea to me. All books are $2.50, and to be found in the American history section, on the floor in a box marked "blogged".
Major Problems in the Era of the American Revolution 1760- 1791, edited by Richard D. Brown (1992)
Major Problems in American Indian History, edited by Hurtado Iverson (1994)
Major Problems in American Urban History, edited by Howard P. Chudacoff (1994)
Major Problems in American Colonial History, edited by Karen Ordahl Kupperman (1993)
Major Problems in American Environmental History, edited by Carolyn Merchant (1993)