All this then sent me researching Richard Thayer...
The Richard3 Thayer who married Rebecca Mycall was grandson of the immigrant Richard1 Thayer of Thornbury, Gloucester, England who emigrated about 1641. (Also too late for PGM.)
While documenting HIM, I came across this:
"Ancient Iron Works in Taunton," in NEHGR 38:266
In 1653, an iron works was being formed in Taunton. There is reference to the suspension of an iron works in Braintree (home of the Thayers) in 1653 (!)
"Additional records show the names of ... [many men]... Richard Thayer of Braintree-- contributing from L20 to L5 each, for whole, half and quarter shares."
This is referring to a document from 1653, and implies that one of the (many) Richard Thayers was investing in the iron works. Later text implies this was Richard2 Thayer, son of the immigrant and father of the husband of Rebecca...