Nothin' wrong with pillows or blankets...just keep in mind all the variables involved, like how thick the pillow or blanket is, how much of the head is covered, how much pressure is being exerted against the heads. Too much of any of these will choke the drum. Probably better results would come from a blanket carefully folded so that it lays flat in the bottom, touching both heads and covering up to 3-4 inches, with light pressure. Some pillows (IMO) tend to be way to thick, reducing the volume and resonance too much. 

On second thought, maybe pillows AND blankets would be handy--in case you get drunk and pass out on the gig.