盤 (Kanji for tray / basis)

also means foundation or basis - makes sense if you think about a tray as the foundation for your lunch.

Onyomi

BAN	Let's BAN trays made of asbestos!

Generally, plates are put on trays in the cafeteria.

ばん	tray LAZY ★★☆☆☆

円盤(えんばん)

a UFO ★☆☆☆☆
円 (yen/circle) + 盤 (tray / basis) = 円盤 (a UFO)

基盤(きばん)

the base or foundation ☆☆☆☆☆
基 (basis) + 盤 (tray / basis) = 基盤 (the base or foundation)

the base, basis, or foundation