Hi mjjss3747,
Most groups will acknowledge a retiring staff person, especially if it is someone who has been in the school community for a long time. As always, it's important to be aware that if you are spending any of the PTO money on this, some parents could object that it is not part of the PTO's mission. Mum24kids touches upon the idea of a homemade gift. Also, you could consider hosting a small get-together after school as a way for parents to stop by and say their goodbyes. Ask some parents to donate a few snacks and refreshments, and it could be a lovely event for almost no cost.
Our high school PTA gives each retiring staff person a $25 gift card. But this is a pretty rich PTA. I've got kids in several other schools and have asked around at a couple of neighboring schools, and none of the other schools give gifts. One of them said that they do give out greeting cards (made by a very talented crafty mom who makes her own Christmas cards, etc.), but most said that they had never even thought about doing anything for retiring staff. Not that it's a bad idea, though--but people seemed to think that sending a card was about all they would do.
Just wondering how common it is for the PTO to give staff retirees anything -- whether it's just a congrats card, a gift certificate, flowers? Or do you do nothing at all, leaving it up to their fellow staff members?