Old squirrel hunter here and the season opens in a little over a week. That means I have an eye out for ripening hickory nuts about this time. Yeah, they appear to be loaded this year.
I guess your pig nuts are what we call spignuts with the stress on the first syllable. Small, bitter and inedible but squirrels love them. We also have what we call a scaley bark, very delicious with a medium size nut that is easy to crack.
Most common is the shellbark, huge trees with the largest nuts but a shell as hard as a rock. These are the favorite of squirrels and classic squirrel hunting is to sit under one of these with ripening nuts on opening day, before daylight, with a true shooting 22 in hand. About first light the limbs begin to shake with arriving squirrels and with luck and a good eye you will have your limit by 8:00 or 9:00 AM.