"Common Yellow Oxalis, Yellow Wood Sorrel" by milesizz. Creative commons.
Don't even think about wishing on
my green hearts. They fold
like the wings of three butterflies,
heads in a huddle. Never four,
not like the one you think I am
when you spy me under
the redwoods' emerald umbrella.
They don't call me sour grass
for nothing. In the wood I am sorrel,
a word like a mouthful of spring;
at home I choke your tender
peas and parsley for all I'm worth.
With each drift of yellow petals
I'm building up my buttercup brigade.
Go on. Pull me. I like it so much I
shower seeds so I can do it again.
Smother me with your thickest mulch;
I will dig my way into the sunlight.
Purge is another name for propagate.
When you found me, you were right
on one count: I can change your luck.