Possession or contraction

My grammatical bête noir is the comma but the apostrophe is an equally tricky punctuation mark. I couldn't resist "Bryns Egg's" on this wayside stall. Situated on a single track road in a fairly remote corner of rural Radnorshire it can't get much passing traffic. Despite this, a glance inside the stall reveals an order form for some singular fungi including Shiitake, Wood Oyster and "Lionsmane" (rather than the conventional "Lion's mane"). My blip  today is another entry in my growing collection of wayside stalls. One day I may have enough for a photobook.