Of course the US has a culture. No group of humans can not have a culture, by definition. Culture is a concept we use to pull together ideas about how a group of people interact in a characteristic way.
The US does many things to acculturate our children and newcomers. We teach them civics and manners and how to shake hands and how to use a toilet and a dishwashing machine and a refrigerator. We teach people how to vote and what voting means. We give people common cultural references by showing things on TV and mentioning them on the internet.
Fluther has it’s own particular culture which is enforced by moderators and by the structure and purpose of the website.
There are no components that all people in the US share. But there are elements that are shared by a vast majority of people. Television watching is one such component. Social group meetings, such as church breakfasts and American Legion chicken fries and various forms of fried dough are common to most Americans. Baseball games, football games, a disdain of politicians, a fascination with weather reports and disasters of all kinds are common to many Americans.
There are a gazillion other things I’m sure we could mention that a large proportion of us share. However, I don’t think it would really help you. I think that the answer to your question would be perfectly obvious if you realized that culture is an emergent thing, and not something that can be imposed. We look at human behavior, and whatever we notice becomes a component of culture. There is no cultural litmus test for being American. People will try to say there is one, but those people are generally small-minded and fearful of anything that is different. But that’s typical around here, and in fact, is one thing we often see in the American culture. Not something we should be proud of, but culture is not about being proud. It is about describing how people behave.