When one is learning to draw, cups and boxes and such things
of simple shapes are good items with which to start. But
then one needs to have more challenge with interesting shapes.
I have found that stuffed animals serve this purpose well.
They come in very simple shapes, but then some have limbs
that are jointed, or long flexible limbs that give posing variety
to them. The yellow bear in the middle of this photograph
was a lucky find in a supermarket! He can take all manner of
positions and presents a good challenge for drawing a shape
that breaks the bonds of symmetry! Also, his modeling rates
are very reasonable!