Forget the sweet image of the bimbo in the, albeit strange, garden. The nursery rhyme of ‘Mary Mary’ refers to Mary Tudor, queen of England after the death of her father and brother.
The line ‘how your garden does grow’ ( which has been subtly altered over time) refers to the growing number of graves in Catholic England during Marys’ reign, as she tried to re-instate the Catholic faith as the one and only to the people. It’s estimated that between 300 – 1000 protestants were tortured, burned and killed by her policy of religious reformation ( numbers vary greatly, but seems to be leaning toward the latter).

The mention of ‘Silver bells’ and ‘Cockle Shells’ refer to the instruments of torture. ‘Silver Bells’ denote the thumbscrews, and ‘Cockle Shells’ were devices attached to the more sensitive parts of the male anatomy and used to apply great pressure until something, or someone gave in.
A ‘Maid’ was a colloquialism used to refer to a device that was the pre-cursor to the guilliotine.

Sounds like someone wished Midol had been invented a few years early.