Ashley Talbot, 15, was struck by the bus at Maesteg School, Bridgend county, on 10 December.
The Rev Bev Reaney read a written eulogy from Melanie Talbot to about 250 mourners at St Cynfelyn Church in Caerau on Tuesday.
"I am sure he will remain in all our hearts forever," the tribute said.
Ashley, a budding mechanic and motocross fan, was buried at Cymmer Cemetery in Croeserw.
In her eulogy, Ms Talbot said: "Don't get me wrong, Ashley was no angel - but he was our angel.
"Ashley was our son - handsome, funny, and no-one could love him more than we did as a family. "
A coroner's hearing into Ashley's death has been opened and adjourned. A police and health and safety investigation into the incident is continuing.
Ashley was hit by the school minibus as it was being driven to a rugby game by PE teacher Chris Brooks.

One officer was killed and 10 people injured as police and occupiers confronted each other.
Locals occupied the mine and refused to leave until the miners paid them a "tribute".
They allege that the mine lies on their ancestral lands and they should be compensated by those exploiting it.
There are conflicting reports as to how police Sergeant Jose Luis Quispe died.
A lawyer for the miners said he was pushed over a precipice by the squatters.
But one of the squatters said the officer fell as he was fleeing the clashes.
Other witnesses said Sgt Quispe lost his balance after the protesters threw an explosive device in his direction.
Interior Minister Carlos Romero said his death would be investigated and those responsible would be punished harshly.
One of the occupiers told local radio that the violence was triggered when more than 200 officers were sent to evict them.
He warned that if the officers were not recalled, locals would block roads.
He said that the miners had tried to convince locals of the benefits their work would bring to the community.
But he insisted that locals wanted compensation from the mining co-operative.
The government on Tuesday welcomed the release by the occupiers of four police officers they had been holding hostage since Monday.
The mother of a Maesteg teenager who died after he was hit by a school minibus driven by a teacher described him as "our angel" at his funeral.
[NEXT_CONCEPT]
Police in Bolivia have clashed with protesters they were trying to evict from a gold mine 200km (125 miles) north-west of the city of La Paz.