I had a great deal of difficulty with this photo but I now feel confident I have figured it out. There are some notes on the reverse of the photo stating that it was taken in 1902. The men appear to be wearing some type of flower arrangement suggesting it was a family event. We know that Wesley J. Powers died in 1902 so perhaps they were attending his funeral in Illinois and since he was a Civil War hero it was probably seen as an important occasion. The other big family event that took place in 1902 (July 4) was the re-dedication of the grave of Abner Powers, a hero of the war of independence. See the posts on Abner Powers and Wesley J. Powers
Names written on back (but notes seem to have been added much after the event): John, Charles, George, Edgar.
I have now found an obituary for Wesley and I feel more confident that this photo was taken at his funeral. The obituary provides names of people attending. Among them are: Ulysses Thornton of Leland, Thomas H. Powers of Orono (who was traveling by train and knowing only that Wesley was sick, missed the funeral – so you might ask – how did he get in the photo?). James Powers (a cousin) of Chicago is mentioned as well as another cousin, Ambrose Powers of Wisconsin. In addition, Frank Thatcher (who is a brother of Mabelle’s husband, Dewitt) , Charles Bishop of Hinsdale, R. B. Wilson of Austin, and Charles Coburn (husband of Delphine Thatcher). Simon Powers , age 75, and Henry LaRue Powers, age 87, (both uncles of Wesley, although the newspaper refers to them as cousins) are mentioned as well as C. Jonas Thornton (a cousin) but the newspaper does not state explicitly that these three were in attendance, although Jonas is the man at the bottom left. (The names appear to have been added at the end suggesting the type had been set but there was space to tuck their names in). Also in attendance were Mrs. Homer Thatcher and Cora Thatcher. We see by the names that the guests were mostly of the Thornton/Powers family and the relations of Mabelle’s husband.
Please see additional posts for Wesley Powers and for James Powers.