found 3 of them in a totlot about 4 inches down they say jacob reed s sons phila on the back of them. they are slightly bigger than a quarter and are brass colored.
Additional info beyond the simple one-year date (1880) at the link posted by Catfish:
The EXACT name in the company-backmark is the key to accurately dating your buttons. Although the firm of Jacob Reed's & Sons (a clothing-maker) was originally established in 1824, it was out-of-business in 1877. It was re-formed by his sons (without the dad Jacob) around 1880. It's name then became simply "Jacob Reed's Sons" (without the "&") ...and stayed that way until the firm went out of business in 1983. Your buttons' backmark says "Jacob Reed's Sons" so it dates from sometime between the early-1880s to as late 1941, when the US Navy changed the emblem on the button slightly (by making the eagle's head look in the opposite direction from what is on your button.
Note that instead of having the usual loop for thread, your buttons have a two-hole "self-shank" on the back. That is typically a characteristic of 20th-Century buttons. Also, your backmark's lettering is written in "plain block" letters instead of having serifs on the letters. In most cases, that means 1890s and later.