Postgres - Generate Series of dates

Below SQL generate rows of first day of months between 2010 and 2012

select (yr || ''-'' || mnt || ''-'' || 1) ::date as dt from(

(SELECT t.z  AS yr FROM generate_series(2010,2015,1) AS t(z)) z

cross join

(SELECT u.y  AS mnt FROM generate_series(1,12,1) AS u(y)) y

)p