What type of wood are westbury drum shells made of?

Westbury is a budget drum brand. Most drums at that level are made from Philippine Mahogany (lauan). This is not "real" mahogany, it's a cheap wood. Basswood is another cheap wood, but better sounding than lauan. Poplar is another common budget drum wood, although back in the big band days poplar was one of the most common drum woods. Those classic Pearl Exports from the 80's .... poplar.

All that said.. the Westbury's are likely lauan or basswood.