Friends in high school????????

I'm a senior in high school and have known these people for a while and am friendly with them but not very close and I want to integrate myself into their group. I started buying presents for their birthdays and Christmas coming up, do you think sitting at lunch with them would help? The thing is I'm really shy and i know they like me because Im nice to them but I don't talk much and I don't know if that will keep them from ever getting invited to do things with them. Like is it ok just to ask? About the gifts I don;t really mean it to buy their friendship (some people said that) just to help a little. besides I like getting gifts for people it makes me feel good. and I want them to know that I like them because sometimes I come off as unfriendly I think because I'm shy.