Hoshi Sato's uniform featuring buttons
A button was a type of fastener for clothing.
22nd century Starfleet uniforms undershirts featured buttons. (ENT: "The Andorian Incident", "Fortunate Son" et al.)
When Clara Sutter explained her imaginary friend Isabella to Deanna Troi in 2368, Isabella was described as wearing a blue dress with white buttons. (TNG: "Imaginary Friend")
In 2370, Elim Garak compared the ease of fixing computers to that of sewing on a button. (DS9: "Cardassians")