This may change, but here's what I've come up with so far:

Sonic (Modern) - Depending on whenever he gets credits for blood donation, he'll either give him a chili dog or he'll give him a couple of his rings that he has with him.

Classic Sonic - Most likely the same as above.

That's...about it for now. He did just join a while ago so there isn't a lot of people he would give gifts to yet.