As i was reading part one i thought it was wierd how clarisse took a dandelion flower in her hand and rubs it under his chin, and then tells him that if the flower leaves yellow powder, it means he is in love. But after she rubs it on his chin it left nothing, so then he becomes angery. How would that make him feel about his relationship with Mildred?

I think Bradbury uses the dandelion to represent Clarisse's innocent and curious personality. I don't think its so much about love for Mildred in that passage, but love for life and noticing the little things that Montag used to walk right by every day without actually taking in. Since their society is so obsessed with technology, he wouldn't usually notice something as small as flowers or rain.Clarisse was able to give Montag a better realization of the world's potential for greater and different things.