Any of several other similar plants. (See below)
Matricaria recutita (formerly known as Matricaria chamomilla), German chamomile or Hungarian chamomile, with fragrant flowers used for tea, and as an herbal remedy.
Chamaemelum nobile (formerly Anthemis nobilis), English chamomile or Roman chamomile, a ground cover with fragrant foliage.
Any of several plants that flower in May - especially the hawthorn (in Britain) and the trailing arbutus (in the US).