A friend of mine, for a snake/terrarium party (we lived in Florida), did a play snake of nicer quality with a tag - “thanks for coming to Marlo’s party!” Or some such words.
It was a good idea. Each of my 3 kids loved those snakes for a couple of years.
I *have* tried to do this, and it gets hard depending on the theme of the party.
We once did a late-night non-sleepover with our young dd. We sent them home with a Duck donut for the morning. I put them in cellophane bags, shut with a nice label. That was the party favor, and I think it worked too.