"A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes also occur. A concretion consists of the same material as the rock around it, plus the cementing mineral, whereas a nodule (like flint nodules in limestone) is composed of different material. Concretions can be shaped like cylinders, sheets, nearly perfect spheres, and everything in between."
The first stone looks like a pudding stone. The second stone doesn't look like a fossil to me but I'm sure someone here can give you a better answer. You might try posting on the ROCKS/GEMS FORUM here. http://www.treasurenet.com/forums/rocks-gems/