Gallon
milk jugs. Drill a couple air holes in the bend of the handle, and then several water holes in the shoulder opposite the handle. The smaller you make the holes, the finer the
shower of droplets that will come out. Something like 3/32" or 1/16" works quite well and can give the light shower you are looking for.
At least this junk is
free junk, so no prob if it wanders under the
lawn mower.