James Boyd married Martha Alexander May 1834 First Garvagh Presbyterian Church.
The marriage took place on 2 May 1834. Where did they live after they were married? Why are you interested in finding these families? are they connected in any way to your previous Boyd posts?
Few early records survive. First Garvagh is fortunate to have kept many of theirs but there are still gaps. And when dealing with common names (both Christian names & surnames) is is extremely easy to make assumptions which can result in following the wrong family.
Starting with the Alexanders, since marriages usually take place in the bride's church, the 1825 church Visitations show Alexanders in Moneydig (more than 1 family) & Movenis- but remember these records are NOT complete. One of the Moneydig families have a Martha BUT this may or may not be the correct Martha Alexander.
The Visitation and other early 1st Garvagh records have been (badly as I'll show in a moment) transcribed and are online. The only possible Boyds are in Inshaleen (no James) & a Bays (I agree more likely to be Boyd) which the transcribers has listed as Move Misagher being possibly Movaghagher (near Kilrea)- the townland is actually Meavemanougher (often written as 2 words).
Between 1830-1838 there are 9 other Boyd marriages but there could be ones which took place in other local churches, There are also 6 Alexander marriages between 1830-1836.