I often use rice when blind baking... and then I throw it out which is obviously a waste. Am I able to keep the rice and either use it again for blind baking or even to cook and eat later?
I have cooked rice that was used for weighting a pie crust with fine results. I should have cooked some that wasn't baked to see what the difference was, but in any case it turned out fine. Of course it may matter what temp the rice was baked at and for how long, and this could also affect the duration needed to cook the rice itself.
I have also boiled beans that were previously baked, and they turned out fine, too.
Whether using rice or beans (I've used both) you first want to line the pastry dough with parchment paper or foil and then place the beans or rice on top.
You can re-use either over and over. I have dried beans that I've been using for more than a decade. Just let them cool completely before placing into a coffee can or other such storage container. If you put them in the can while warm they will produce condensation and then get musty and stinky. Make sure they're labeled so that no one tries cooking them. I know Kevin said he's cooked beans that had been previously baked but the more you bake them the drier and harder they're going to become.
I prefer beans over rice due to the small size of rice. If it should fall onto the dough on the bottom of the crust while removing the paper/foil, it is hard to removed and can easily get pushed into the dough in the process (depending on how much it had been blind baked...usually you remove the weights and continue to cook the bottom for browning/crisping.
I actually sprung for a few sets of ceramic pie weights, because I got tired of beans occasionally sticking to the crust, and then having to worry about storing slightly-used beans separately from their unused kin.
I'd say there would be no problem re-using it in the short term. I'd watch out in the long term though: rice is really hygroscopic, and once it gets a little water in it, it won't be good for long.