Can anyone point me to a website that would have a list of common lumber
sizes? I'm thinking about making a basic woodworking bench and I'd like to
compare common lumber sizes to various plans.

Being a newbie, whenever I get to my local lumber yard I get overwhelmed by
all the choices so tough to figure out what I want in advance. And when I
try to figure in the size difference between nominal and actual sizes my
head spins!

thanks in advance