To figure out when she was born we probably need to know her maiden name. The linked rootsweb page claims that she married John Gent in Salem in 1642. So a guess for her birth would be circa 1620. Salem was founded in 1626 so she wasn't born there. She likely wasn't born anywhere in Plymouth Colony since it was founded in 1622.
The Geni group, Early Families of Salem, Massachuetts has a list of early citizens so I looked at the ones with Geni profiles to see if any had daughters who might have married John Gent. I found several that had daughters named Elizabeth but most were too young or had husbands who lived past 1642. I found one promising candidate, Elizabeth Stileman who was born in 1621 to Elias and Judith Stileman in England. So far I haven't found out anything more about her.
At archive.org I found several volumes of "A genealogical dictionary of the first settlers of New England" which showed the marriage of an Elizabeth Stileman, but that was her niece.
Another idea is that maybe Elizabeth Spear was a native. That could explain why she was able to make such a large land purchase at Sheepscott. Unlikely, but possible.
https://www.geni.com/projects/Early-Families-of-Salem-Massachuetts/...
http://freepages.rootsweb.com/~walkersj/genealogy/ElizabethGent.htm
Maine settlements are very interesting, because there was traffic from seasonal fishermen years before the founding of Plymouth Colony. And with the mentions of her “social class,” I’d bet on -
- English birth
- family affiliation with one or more of the English “undertaker / adventurers” affiliated with the Sir Ferdinando Gorges companies
I think some of the Early Families of Salem were pretty well off too. I wonder if the town records that old are still around. If she moved directly from England to Maine then it would be odd for them to go all the way to Massachusetts to get married. Or maybe there weren't any churches yet in Maine.
It looks like Elizabeth Stileman isn't Madame Gent after all.
Her parents and brother Elias Jr. sailed to the new world in 1630 as a part of the Winthrop Fleet. It was just the three of them without the youngest 5 children. They were too young to leave on their own. Apparetly they all died as children? After their births I don't see any record of them in ither Salem or London.
The exception is the oldest 'daughter' Alice Sharp who was born 9 years before Elias was married. It turns out that she's his neice. I've started a discussion in her profile to fix that.
Here's the Winthrop Fleet Passenger list that I forgot to paste.
https://familypedia.wikia.org/wiki/Winthrop_Fleet_Passenger_List