Perhaps an idea you haven't thought of is a leaf baby!

I know teachers that love these, I talk to them at fairs and events and often they go home with a little one to be a class mascot (Maple class, Oak class etc).

They are also very good to support the forest school learning they do with the children - I have a pack of 10 leaf baby cards too.

So instead of a mug, or a bottle wine, or a box of chocolates give a little momento to remember their class of 2025 by!