Dear Client,

A most unusual spider indeed.

Your spider is in the orb weaver spider family- Araneidae.

More specifically it is the arrowhead spider, Verrucosa arenata. I suspect that you can see how this spider got its name.

https://en.wikipedia.org/wiki/Verrucosa_arenata

http://bugguide.net/node/view/2035

All spiders are considered beneficial outdoors.  Some people are not so happy when they get indoors and consider them a nuisance.  I would just gently capture and release it outdoors.  It is not poisonous to mammals , but I would avoid handling any spider.