It may be possible to grow rice from grocery store rice, if it’s fresh enough. Look for organically grown long grain brown rice; many home gardeners find the organic brown rice tends to sprout more than conventional varieties of long grain brown rice from the grocery store. You won’t be able to grow rice from white rice, polished rice or parboiled rice, because these types of rice have been processed. Generally though, it’s best to purchase rice seed, as it’ll be guaranteed ready to grow.