It is VERY important that we be extremely careful with placing objects on the flatbed scanners as the glass can scratch easily. Please use protective clear acetate if you are scanning objects that could damage the glass on the flatbed.
You can scan more than one object at a time and separate them later in Photoshop.
Les Rudnik says "The photogram is truth. It represents the pure interaction of light with an object." He has a great site called "Photograms - Art and Design." "The History of Photograms" is a very interesting set of pages.