Mr. Radley fills in the knot hole
an oak tree
gum
boo radley
a halloween pageant
it represents jem's childhood
Boo Radley secretly placed them there.
Tree and flowers
Yes.
a key
Some examples of idioms in "To Kill a Mockingbird" by Harper Lee include "bought the farm" meaning to die, "cry over spilt milk" meaning to regret something that has already happened, and "barking up the wrong tree" meaning to pursue the wrong course of action.
Boo Radley
it's in chapter 6