In NY, Polo Grounds dirt is worth something, not Citifield, its only 5 years old.
Probably not much at all. Citi field isn't that old and frankly, the dirt probably isn't all that hard to come by.
Not a cent. Even if it could be proved it came from Citi Field, which it can't, it still would have no value.
Not much, Citi Field is a newer ball park and it is still in operation. Its also not like a seat or something cool.
But if you like it, might as well keep it, I sill think its kinda cool
Oh, religious believers will pay you a lot for it. They can make people out of dirt.