"This page is being set up to help meet the unexpected costs which arise from a bereavement."
Lucas was described as an angel taken too soon in a bereavement notice in the Hawke's Bay Today yesterday.
On the Givealittle page, donors were offering their love and support to the Mildenhall family.
"Our darling Lucas, gone but never forgotten. You took our hearts with you. Love you lots. Jen and Shane we are here for you in every way," one said.
"From a school mums eye, you were always smiling and reflected all the school's values. So Incredibly sorry for your loss," said another.
Police were alerted to the missing child at around 4pm on Sunday and he was found a short time later.
Lucas is said to have suffered head injuries.
The Trust Tairawhiti rescue helicopter was called to fly Lucas to the property homestead from where he was taken by ambulance to Gisborne Hospital.
Police have investigating on behalf of the coroner.