Your DNA matches have nothing to do with your tree. They match your DNA. Period. You are scientifically proven to be related to them. Your tree and your matches' trees are just paper trails to use to try to determine what that relationship is. In many cases the relationship may not be known either because one or both of you have not researched far enough back, or one or both of your have faulty research, or one or both of you have not researched collateral lines or there was a paternity event, an adoption or illegitimate child.
A lot of people from England show some Scandinavian because England was invaded by the Norse centuries ago. Just because your ancestors stayed in England does not mean that some of your kin did not come to America long before your family did. You may be able to help them determine where in England their ancestor came from.
I was contacted by a person who has a Chinese parent and an Irish parent. If a mixed marriage occurred centuries ago in one line, it is going to be reflected in that person's ethnicity results. A person of a totally different race can still share that small segment of English DNA with you that goes back centuries.
Try not to be discouraged or frustrated. Focus on the matches that you may potentially be able to figure out, the ones with shared surnames or places. Once you learn more, you may be able to figure some of the others out, but there may be some that you never figure out simply because records do not exist to confirm the relationship.
Hope this helps.