 He also had an estate in Coconut Grove, Florida, and created a coconut plantation on the northern two-thirds of Key Biscayne, an area now occupied by Miami-Dade County's Crandon Park and the Village of Key Biscayne.William's older son, Hugh Merrill Matheson, was an early student at Ransom School and William donated a building to the school; the Matheson Infirmary.In 1930 William donated 80 acres to the county which was named Matheson Hammock Park.