Acorns - Are they bad seeds?

Sam had been collecting acorns for Etan. Do you remember Etan, he's the kid that has taught my kid lovely words like kill and pummer. They aren't even in the same class! They only see each other on the playground and if there are special events going on. So from what Sam tells me he gathers them to give to Etan for his collection. They call then super balls or beads. Part of me feels like telling Sam, I don't like that kid and you shouldn't either! Like when he asks if he can go to his house or have him come to ours. Instead, I say I have to talk to his mom and I don't know her phone number. Which is true, I don't know it but I could see if it's in the student directory. I know that this is the first of many kids that I will feel like negatively influence Sam. What I don't know is what to do? I do know that there are other moms that feel the same way.