Lammas or Lughnasadh (/ˈluːnæsə/) is the first of the three Wiccan harvest festivals, the other two being the autumnal equinox (or Mabon) and Samhain. Wiccans mark the holiday by baking a figure of the god in bread and eating it, to symbolise the sanctity and importance of the harvest. Celebrations vary, as not all Pagans are Wiccans. The Irish name Lughnasadh is used in some traditions to designate this holiday. Wiccan celebrations of this holiday are neither generally based on Celtic culture nor centered on the Celtic deity Lugh. This name seems to have been a late adoption among Wiccans. In early versions of Wiccan literature the festival is referred to as August Eve.
The name Lammas (contraction of loaf mass) implies it is an agrarian-based festival and feast of thanksgiving for grain and bread, which symbolises the first fruits of the harvest. Christian festivals may incorporate elements from the Pagan Ritual.
Content taken from Wikipedia, whilst we find the time to translate the information into a more pagan format