Please answer a question about the following article about Buckingham Palace:

Various owners leased it from royal landlords and the freehold was the subject of frenzied speculation during the 17th century. By then, the old village of Eye Cross had long since fallen into decay, and the area was mostly wasteland. Needing money, James I sold off part of the Crown freehold but retained part of the site on which he established a 4-acre (16,000 m2) mulberry garden for the production of silk. (This is at the northwest corner of today's palace.) Clement Walker in Anarchia Anglicana (1649) refers to "new-erected sodoms and spintries at the Mulberry Garden at S. James's"; this suggests it may have been a place of debauchery. Eventually, in the late 17th century, the freehold was inherited from the property tycoon Sir Hugh Audley by the great heiress Mary Davies.

What product did the mulberry garden produce?
silk