NO - NO - not to put in the microwave - these are made for a game that you play outside - you throw them - kind of like horseshoes - but you throw them on a wooden board thingy with a hole in it - and get points if it goes into the hole or how close it gets to the hole, etc.
There are other kinds of bags with corn, rice, beans, etc. in them that you put in the microwave for aches and pains.
HTH