For mine I used the backpack, with plants inside boxed. You might just need to be creative, I had the thought of using a tackle box with the inner shelves removed, but reconsidered when I would also need to bring a fishing pole.
I went out very early in the morning when few were around. Looking suspicious and scared will get you in trouble.
I was worried until I thought of all the times people have stopped me and asked what was in my backpack.....none.