I am stunned that some are appalled. I admire the OP. She took the time to acknowledge the gift in a personal manner. I would be stunned, but happy if more teachers acted in the same manner.
We have NEVER received a thank you note from any teacher, administrator, a office clerk, no one. This is both at private and public schools.
The home address was used at it should be. It was given for the use of school. The teacher works at the school.
Solicitations are not OK by any means, this was clearly not.