The time of year when the wheel turns to Lughnasadh historically is a gaelic festival celebrating the beginning of the harvest season. I celebrated personally by going out to the garden and tending to the plants! I have some nice muscato grapes growing on our vines, so I had picked some clusters to try and also use along with other fruits, flowers and vegetables to decorate my altar for the sabbat-ritual.
I baked a "harvest cake" to celebrate the event; making it simple but delicious, and sharing with friends, family and our neighbors. I also cut a piece to put on a plate for my altar as an offering.
I also decided that I wanted to make my own type of mundus, or a type of offering-pit used in roman times for specific purposes. I dug a simple hole in a patch of earth in my plot and with simple oration and due praise, I buried the offerings I had picked from my garden in the soil to my deities-of-choice. I had an image in my mind afterwards as if the earth-pit was a belly that had been fed and now is filled-up: the earth was happy, and I could feel it.
Generally, these harvest celebrations I would imagine would be celebrated during the light of the day, when the Sun is high. For me, I celebrated in the night. Dancing around a circle, incense thick in the air, candles casting dozens of equally-dancing shadows around. The night went well, and the gods were pleased.
The Altar, decorated with a cornucopia of harvest fruits and vegetables; incense and candles, flowers decorating~