You are right to say that the past perfect is used to sequence 2 past actions with one event occurring before the other.
When two actions occur close together in time, the past perfect can be used but it is more common to use two verbs in the past simple. In your example, the words “soon afterwards” indicate that the two actions occurred close together in time.
So you could say “His wife had retrieved it from the rubbish bin, and soon afterwards it was accepted for an award”.
Or “His wife retrieved it from the rubbish bin, and soon afterwards it was accepted for an award”.
Both would be correct with the second sentence being more usual. In your past perfect sentence, both verbs are in the past perfect and so this is not correct.
I hope this will help; the past perfect is not an easy tense to teach.