Pyrite commonly forms in sedimentary environments and takes the form of balls and rods with crystal faces on the outside. Occasionally you might see them as micro-crystals in concretions, but that is not where they usually form. Some pyrite that forms this way has a reasonable value, but I can only think of 2 or 3 localities in the USA where this is so. Most specimens will be $1 to $15 at rock shows. Also, sedimentary pyrite is inherently unstable and if kept in humid conditions can deteriorate into sulfuric acid and powder. Another reason why most people don't collect too many of these crystals.
Please post some photos of your specimens.