- I helped James move house this week and he sent me a big bunch of flowers to say 'thank you'.
Look at the sequence of events in Q1.
1st: I helped John move house this week.
2nd: John sent me flowers as a thank you gift
According to the sequence of events, it would make sense to make the first verb in the past perfect tense, the act of helping a friend move house obviously occurred before receiving the flowers.
- I had helped James move house this week and he sent me a big bunch of flowers to say 'thank you'.
However, the order of events listed match the sequence.
A) I helped John move house
B) (then / and) I received a bunch of flowers.
There is no need to use the past perfect in the first clause as the past perfect is normally used to clarify the sequence of events, that is when a past event precedes another past event.
If I wanted to use the past perfect, but there's no reason why I should, a better solution would be to change the order and the conjunction used to unite the two different clauses.
- John sent me a big bunch of flowers to say 'thank you' [why] as / [when] after I had helped him move house.
This also explains why the sentence in Q2 is grammatical and appropriate.
- [1st] My mother phoned me three times this morning [2nd] and then this afternoon she came round to my house.
What are the real rules for choosing between the simple past and past perfect when both actions are in the past?
Shouldn't the first verb in “she died before I was born” be in the past perfect?