Lammas is coming up this week (it's on Tuesday 1st August) so I thought I'd do a celebration ideas post to accompany my past ones on Hallowe'en/Samhain, Oestara, Beltane and Litha. (Read them as well if you'd like some ideas for future celebrations, the closest is Samhain in October!). It's my favourite sabbat apart from Samhain aka Hallowe'en! :)
The main themes are harvest and the Sun God Lugh (pronounced "Loo"). At Lammas he's slain and will be resurrected at Yule in the form of the new God (much like the Christian Jesus). Some people make a Corn King to represent Lugh.
Here are a few links with more info about Lammas aka Lughnasadh (also click on Lammas at the start of the post to read more about it):
Update 1/8/24: I've updated/replaced some links.
https://www.goddessandgreenman.co.uk/blog/lammas
https://www.learnreligions.com/celebrating-lammas-or-lughnasadh-in-august-2562156
https://thepaganandthepen.wordpress.com/2010/07/31/lammas-corn-king/ (Currently a private site)
https://www.sagegoddess.com/blog/musings/simple-ritual-ideas-lammas-first-harvest/ (Updated in 2022)