Is there any use for 300 double density disks that you creative guys can think of? 
You could make a tech room wallpapered with dd disks.
Upload it to the net and I bet you would get some nice comments ;-)
If you have some funny colour ones you could make a mosaic
Or do 300 art projects like putting a floppy disk over the top of a glass and melting it so it folds like a piece of silk etc.
As for do they have a value, yes but its not normally hihg enough to cover the cost of postage :-(