Quotes From Chapter 6

First quote: 'Don't get in a row of collards whatever you do, they'll wake the dead.'

Second quote: 'Shot in the air. Scared him pale, though. Says if anybody sees a white nigger around, that's the one. Says he got the other barrel waitin' for the next sound he hears in that patch, an' next time he won't aim high, be it dog, nigger, or - Jem Finch!'

Meanings:

For the first quote, collards are smooth-leaved kale. The sentence may mean that Jem, while they are climbing under the wire fence should not step on the smooth-leaved kale to avoid trouble from anyone from the Radley's residence that led to Scout, Jem and Dill hiding. Jem then lost his pants due to the struggle in the fence. Miss Stephanie then questioned Jem on where is his pants when Jem replied that he was playing strip poker. Miss Rachel then flared up thinking that Dill was gambling when Jem tried to appeased them saying that they were actually playing with matches.

For the second quote, Mr Radley had shot a Negro. The bullet did not hit him as Mr Radley shot it in the air, high up. What I do not understand is, why did Mr Radley said that if we saw a white nigger around, that's the one. He then said that there is another barrel(a tube through which a bullet travels when a gun is fired),
waiting for the next person to come in the patch and this time will be shooting the person be it anybody.