These are pretty fabric underbed storage boxes from Next (there are 2 boxes identical to the one shown in the photos).  White with pink spots, they can be dismantled and folded up if not required for use.  They are approx 75cmx45cmx20cm each and the lids are separate to the base of the boxes.  With 2 handles on either (long) side of each box, they can easily be pulled out from under a bed.  Both boxes fit comfortably next to each other under a standard size single bed.

These were £50 originally.  Grab yourself a bargain or make me an offer!