Mr Brown looks after his son Alex in the mornings, getting him ready for preschool and dropping him off while his wife works an early shift.
On Tuesdays their rubbish is collected, and as soon as Alex hears the truck he makes a dash for the door.
In his letter Mr Brown said: "Now you could just carry on oblivious to a man and his son in the driveway but no. What you do is take a small moment of your time and wave and say out the window 'hi boy!' with the biggest smile.
"It took Alex about a year but then the day he waved back you were so happy and it made Alex laugh.
"Now every Tuesday morning, Alex runs to the door and leads me out so he can watch and wave at you and as always, you wave back with a huge smile.
"So I thank you Tuakau rubbish truck guy. You might think it's nothing but it makes Alex so happy."
Comments on the post suggest ways for the Browns to find the anonymous "rubbish truck guy" but Mr Brown said whether or not they made contact, he just hoped the man knew he had brightened many mornings for their family. "I just wanted to say thank you."
The thank you letter in full
An open letter to the Rubbish truck guy that picks up our rubbish in Delphi Grove Tuakau
We don't know your name or where you are from. We don't know your story and you don't know ours. I never took any notice of you over the years and like everyone else just expect our wheelie bins to be picked every Tuesday morning and left again in a tidy row for us to put away.
Two years ago it all changed. All of a sudden it was a highlight for us. Every Tuesday morning we hear your big truck coming and the excitement begins. Even before he could walk or talk our son would stop what he was doing and make his way to the front door. I would take him out side and he would look on in amazement as you expertly guided your truck around the cul de sac and picked up each bin with what has become known as your crocodile arm. Now you could just carry on oblivious to a man and his son in the driveway but no. What you do is take a small moment of your time and wave and say out the window hi boy! With the biggest smile. It took Alex about a year but then the day he waved back you were so happy and it made Alex laugh. Now every Tuesday morning, Alex runs to the door and leads me out so he can watch and wave at you and as always, you wave back with a huge smile.
This morning you even out did yourself. I take Alex to daycare every morning and some mornings are harder than others. Today he didn't want to get out of the car when we got there. Then he heard your truck. He instantly wanted out so he could see you. As you drove past you recognised us. You didn't have to, but you did. Again a huge smile and wave. Alex waved back and was so excited to go into daycare and tell everyone about you.
So I thank you Tuakau rubbish truck guy. You might think it's nothing but it makes Alex so happy!!
Aaron Brown