Question: What was in the hat box in the garden?
Question: After Margo was convicted, why did Tony move one of their beds into the living room?
Chosen answer: It's mostly so the audience can see more of Tony's underlying character. This is Margo's bed, and Tony wanted it separate from the bedroom that they shared as husband and wife. Tony is "emotionally divorcing" himself from Margo as he is about to start a new life as a single man. Leaving the bed in the bedroom would serve as a reminder of his guilt in framing his innocent wife for a murder she did not commit. The bed is likely parked there until he can get rid of it.
Chosen answer: I think her head was in the hat box after he dug it up from the garden where the dog was digging under the marigolds.
You are correct that it was her head.
raywest ★