"The lengths some people go to amazes me. Trying to steal money from a charity is pretty sad. What a low life," she said. "Luckily the volunteers had the good sense to ask to see some identification."
The woman couldn't produce any so was asked to leave.
Police have been notified of the incident.
"She was pretty cunning. It's pretty disgusting. Their needs must be pretty bad if they have to stoop to such levels. They are the lowest of the low."
Because it happened outside the store there is no security footage but Mrs Morgan is warning people volunteering on the streets to be careful of being tricked by people like this.
When The Daily Post arrived at the tree yesterday, Rotorua's New Zealand Home Loans staff members Claire Sims and Hayley Johnstone were volunteers for the day.
Both said it was disgusting someone had tried to steal the money which was used to support families and patients through some of the toughest times they would face.
"This time of the year always brings out the good, the bad and the ugly in some people," Ms Sims said.