I have a ton of this growing in my yard. Is it chamomile? If it is, I want to start harvesting it.if not, any clue what it is? Thanks!
No, it's not Chamomile. It's a member of the Aster family of which there are a stack in N America. You could try posting the image on the Name that Plant Forum here on GW for a more accurate id.
It is a very weedy aster. It is one of the "thugs" I rip out with abandon from my gardens. Just like Solidago canadensis which is another thug I rip out of the gardens, they are stunning in wild spaces but not friendly garden plants. Before you bust on me for not liking native plants, I plant many and encourage native plants throughout my property. I also have acres of land left to be wild that are filled with many different aster and goldenrod species - pollinators visit us throughout the season for our wild meadow areas. But some of those wild plants are not welcome in my tended gardens. I would not advise letting this one stay in a garden.
It is not chamomile in the OP's picture. Nor is it related to chamomile other than they are both in the Asteraceae family. But then there are 2800 species in that family. The plant pictured is Symphyotrichum racemosum, Symphyotrichum ericoides, or one of the other white asters.