Am I alone in thinking it should be "is being mowed" because "mown" is a resultant property of the grass? Like being melted and being molten. Or is it one of these things non-native speakers develop a keen intuition for to be able to spot it just to be blind-sided by native speakers not giving a fuck.
I mowed the lawn, the lawn was mowed, has already been mowed... a freshly-mowed lawn. I'm not sure if I'd ever actually use "mown" as a conjugation of "to mow".