basket, square outside and round inside, used to hold boiled grain in State worship
盙 centers on a ritual container for grain: a basket with a square outside and round inside, used in state worship to hold boiled grain.
盙 combines 甫 (possibly phonetic) with 皿 (dish/container), suggesting a vessel for grain offerings. The exact historical development is uncertain.
The top 甫 looks like a sprout growing in a field, and the bottom 皿 is a dish. Imagine a square basket with a round inner bowl, filled with boiled grain from the field, used in a solemn state ceremony.
For フ, picture a priest blowing a soft 'foo' sound over the grain basket to bless it: foo -> フ.
—