Here is a fine cup with a rim divided into seven bracket lobed segments. Due to the resemblance with the marshmallow flower, the Chinese gave these dishes the name of marshmallow with 5, 7 petals (or more, depending on the number of petals) (1). From the flat centre radiate the moulded petals, with a fine ivory and green crackled glaze in the hollows. Five delicate spur-marks.
Pieces with foliated edges appeared at the end of the Tang dynasty in China, in most of the important kilns of that period (1). This model appears to be rare in Vietnam.

References:
(1) Watson, William, Tang and Liao Ceramics, 1984, p.138, cat.115 and 178
https://www.britishmuseum.org/collection/object/A_1915-0409-85
https://collections.ashmolean.org/collection/browse-9148/per_page/100/offset/14900/sort_by/random/object/26442