After Jim's 31 Inf Div clue I found the following:
The gator is from the 124th Inf Reg. insignia which was part of the 31st Div., activated Oct. 1917, sent to France Sept.1918. The div was used as a replacement unit.
From wiki: "It was originally activated as the 10th, a division established in early 1917 consisting of Alabama, Florida, and Georgia national guardsmen. By the end of that same year, the 10th Division became the 31st. In World War II, national guardsmen from Mississippi were included in the division."
155 Inf. Reg. insignia: Mississippi's oldest National Guard unit
167 Inf. Reg. insignia: 4th Alabama"; part of the Alabama National Guard
31 Div. insignia:
So, probably a WW1 31 Div. infantry uniform.