Wedding Invitation

My youngest son handed me a small white envelop the other day. I thought it’s a phone bill, but when I saw it, it wasn't a bill from the telecommunication company. I opened it and thinking that it was a solicitation from school, but I was wrong again. It was a wedding invitation from my eldest son’s best friend. My family is invited for the wedding in September. So, what will I do now, well of course, I need to look for a gift for the said wedding? I have no idea yet on what to give. Is it dinnerware, kitchenware, home décor, wind chimes, or bed sheets, whatever? Anyway, I still have enough time to think about what is the best gift for them that wouldn't hurt my budget.