Richmall Smith was a complete guess, sorry. Because Mary Woods' child was listed as Richmul, Richmoel, etc, I thought I might get lucky and find that Richmul was named after her maternal grandmother. Looks like you ruled out the Bolton couple. Thank you.
I don't know what Mary Woods' maiden name was. The baptismal record states that in 1829 she was a widow, but I'm not sure if her husband passed in the UK of US.
Before the baptismal record was found, many family members in the US mistakenly listed Mary's daughter Richmul as Richmul Jane Fisher, although she had been on a census with Mary Woods and buried in the same plot. The Fisher name comes from a secondary resource and the baptismal record along with the other evidence trumps that source.
Maybe Fisher could be Mary Woods' maiden name, but it could just confuse the issue. After using Fisher erroneously for years, I hardly want to mention it again, although it could be a clue. I kinda doubt it, but I'm probably blinded by irritation.
A cursory look at records makes it seem like a Kay family in Bury used the Ricmael name quite a bit. It looks like it was used in Middleton too, but the range of the name looks fairly limited?
Oh well, I was hoping someone out there might be missing a Mary who married a Woods near Bury and disappeared to America.