Re: i found a hard-shelled spider. black on bottom/whitespecks top hockeymask,

I suspect that you have a specimen of the orb-weaving spider Gasteracantha 
cancriformis (sometimes called a "crab spider", although it is not related 
to the true crab spiders in the family Thomisidae). You are a little far 
north for this spider, but with the warm weather we have been having in 
the United States this year it is not impossible.  See  http://www.ufsia.ac.be/Arachnology/Pages/Pictures/gastera1.jpg for a 
drawing of a similar species.  All orb-weaving spiders in North America, 
including Gasteracantha, are apparently harmless.

Reference:   Kaston, B. J. 1978.  How to Know the Spiders.  McGraw-Hill, 
Boston, Massachusetts.

Admin note:

David Richman later provided the following further information:

I made one mistake on this- I read Iowa instead of Louisiana as I think
the person is from.  In Louisiana it would probably not be unusual to find
Gasteracantha.