As a former Geology Minor college student, and longtime "rockhound," I can assure you the object your found is one of the many varieties of chert nodules, and its specific variety is flint.
By the way... DirtDigler is correct... flint-nodules often weather to a light-grey-ish/white-ish color on the outside. I found dozens just like yours on many "rockhounding" trips to Paint Rock Valley (in Alabama). The streambeds there contained many chert, flint, and jasper nodules, which had eroded out of the surrounding limestone.