umbrellas

[Leah S.]

summer rain
brightly coloured mushrooms
bob above my fence

I never saw a bobbing mushroom...
If I were to nitpick, I would say for the sake of good Haiku, you have to get 'umbrellas' into the body of the poem. Putting it in the title is cheating. Carry on. Leah.
PS.
My favorite Haiku is Basho's
"Clods of earth
seeming to move?
No. Quail."

I would think you'd be more likely to mistake umbrellas for balloons rather than mushrooms. Of course if your perceptions were altered, that's another story......