Forest FC 1863
Forest FC predated Association Football. Formed in 1859 by a group of former public schoolboys under the direction of CW Alcock, they played in a variety of codes.
They played near Epping Forest, hence the name. In 1863 the Forest Club was among the founder members of The Football Association (the FA) and adopted the rules set down by that body, although they continued to play occasional matches under other sets of rules against clubs not affiliated to the FA.
The club changed its name to Wanderers in 1864.
The picture above is the earliest Association team photograph that I have come across.