A fella gave me a rattlesnake skin and besides being flat and oiled with Neatsfoot oil any suggestions on mountining it to some kind of backing for a hanging display.

The usual method is to sew the skin on a piece of felt with about 1" or so of the felt showing. Trim the edges of the felt with pinking shears and it's done.

JDS

A snake skin on a nice weatherd barn wood looks good. A great place to hang it is over a door way, were not much else with fit.
You can add some old rusted nails and hang turkey beards or game calls on them also.
Have some fun with it, and good luck!

Maybe pick up various styles of antique barbed wire to frame it with? Just throwing that out there.