That there is a nice little Date Nail collection. Those were big in the late '60s-early '70s along with RR insulators and barbed-wire. I still have all the nails I collected back then. Even telephone poles had the round type which can still be found if you find an old pole out in the wild. The same for RR ties. I always check when I see old ties being used for landscaping or fenceposts. All the RR tracks in my area have had the ties changed years ago so can't find 'em now plus, railroads don't want anyone on their tracks nowdays.