Found this large button while detecting a property. Most of the coins I've found on this same property are from the 1940s. The backside says, "Art Metal Works inc. Newark N.J."
It is a US Army "Great Seal" button. That basic type was first issued in 1902 and is still in use today. However, yours has a raised rim around the emblem, which dates from 1910 through today. We can narrow down your button's time-range further than that, by dating the company name in its backmark. The "Art Metal Works Newark NJ" company is reported to have gone out of business in 1930. Furthermore, US Army "Great Seal" buttons had "black finish" on the front from the World War One era until 1923. Your button shows no trace of "black finish." Combining all of that information indicates your button was made sometime between 1923 and 1930.
