The ones Yamada made are the round onigiri.
Earth is spherical.
I wouldn’t say that my face is round.
With an い on the end, you can guess that this word is an い-adjective. What is the adjective version of the kanji 丸? "Circle" becomes circular, spherical or round. This, compared to another similar word (円), is more general purpose and can be used with 3D spherical objects as well.
This word uses the reading you learned for the kanji 丸, though you'll need to tack the い onto the end too.