Simply put, the best gifts I ever got were thank you notes from my students. Especially heartfelt ones that were clearly written in the student's own voice. It's particularly great when the child can be specific in mentioning something that I did for him, or a day when he had some kind of pivotal learning experience or success. (Maybe extra help with a paper, an A on a test, or a time when I stood up for him.) You could even write a letter talking about a special conference you had or something.
The teachers I know all appreciate thank you notes best of all. We keep them well after we retire and they remind us of why we do what we do. The feedback also helps me to do a better job. When I'm too tired to call a parent, I will remember the thank I got for making such a phone call and it motivates me. Or I will use the same technique again to try and reach another student.
I am personally kind of uncomfortable with many gifts, especially as a public school teacher. I'm bound by law to treat everyone equally. I also am not supposed to accept things over $10. I am willing to accept small gifts that can be put towards the classroom - like teaching supplies. You cold talk to another teacher in the building to see what the supply situation is like. Different schools and teachers' needs vary. In one district - paper itself was a commodity I had to buy myself out of my own pocket! There are always some items that would help us do our job better, but the district won't buy: reward stickers/stampers, timers, magic markers, extra books, neat gizmos.
Beyond that, there was one gift over the years that I really love. It's a glass apple. The student who gave it to me was a big, tough-on-the-outside kind of kid. The first minutes of the first day he announced loudly to everyone that he HATED my (subject) class. That was an interesting way to start! This basic level student struggled with some basic level work, but absolutely excelled at other skills- better than most top track students two grades above him! That surprised me. I was seriously surprised that mom, who rarely came for any conferences, entrusted him to successfully carry such a fragile gift to school even. This was a BIG kid who regularly crashed into others in the hallway and was suspended for a fight that resulted from his crashing habit. He didn't mean to be mean, he just couldn't handle himself.
Though it may sound a bit cheesy, the glass apple was a perfect metaphor for this kid- tough on the outside, but ultimately fragile. It also reminds me to look for the strength in each students and to build on that strength- as I did with that young man. I sometimes stuggle with kids who are tough on the outiside until I see their softer inside and gain their confidence. I also someties struggle with kids who have never known success in my subject area until I can find their strength. That apple has reminded me more than once to not give up on a difficult student. It's also pretty. The downside is that I couldn't have it on my desk at school.