the pastry on the bottom and sometimes covering a pie
pie-crust
adjective[ before noun ]uk/ˈpaɪˌkrʌst/us/ˈpaɪˌkrʌst/
（衣服）有波浪边高领的
used to refer to a type of high collar that has an edge that is not straight but that curves in and out, or to a piece of clothing that has this type of collar
She was wearing a long-sleeved blouse with a pie-crust collar.她穿着一件有波浪边高领的长袖衬衫。
She cited Margaret Thatcher as an inspiration, which would explain the pie-crust blouses, woolly cardies and A-line skirts.她说玛格丽特•撒切尔是她的灵感来源，这样就能明白为什么会有波浪边衬衫、羊毛开衫和A字裙。
More examples
I bought a green floral pie-crust jumper.
Then I went through a short phase of wearing pie-crust collars.
She decided on an organic cotton pie-crust dress in blue.