I don't think corn has any silver in it and I'm pretty sure the grading companies don't grade it, be it kernel or on the cob.
A maize is what you walk through in the fall. You try not to get lost but you do. It's usually done at night with flashlights around Halloween.
If they are all 40%, 2 bucks a pop to the right buyer. The ones not silver are worth $0.50. Not worth grading unless there was a high enough grade or dramatic error.
Those all look circulated to me. The silver coins are worth melt value, the clad coins are worth 50 cents. The 1964 is 90% silver and currently has a silver value of $6.34 Any dated 1965-1970 are 40% silver and currently worth $2.59 Anything newer than that is clad and worth 50 cents. There are some 40% silver 1976 coins but they were only issued in collector sets and yours doesn't look silver based on color.