Mum had made the dinner. John has had his dinner. Mary had had her dinner before the power cut. Leo may have had too much dinner.
When and why do I use had, had had, has had and have had?
had -past tense simple of "have"
e.g. I had dinner at 8 last night.
has/have had - present perfect simple
unfinished or recently finished action
e.g. Have you had your lunch? Not yet.
She has done her homework this morning.
had had- past perfect simple
action finished in the past before another action in the past.
e.g. I had had my dinner when mother came home.