Zinnias will reseed a bit, yes. it might have been in the soil that the tree was in.

Yep,a zinnia. Just surprising to me, as, of all the seedlings I've found sprouting about, I've never had a border type annual: marigold, pansy, zinnia...till now. Had to be from a bird. I love it.
Marti

Zinnia,one of my favorite flowers.I love alll the surprises the birds and winds bring.
Kathi

My Grandmother would have said " Fairy planted" .