Hawthorn is assumed to be a safe berry to eat. I have read the seeds are not so good, but in most cases, the fruit is consumed and the seeds are passed. Birds eat the fruit and spread the seeds… I have not been able to find any information validating that the seeds are toxic - most likely a legend as history shows that there have been many food and medicinal uses for Hawthorn over the ages.
Okay, so I was out on our dogwalk this morning and decided to eat one of the hawthorne berries. Not good at all! The texture is weird - very mooshy and very little flavour if any. However, I did come across a tree with these smaller orange fruit on them (the size of a large grape). Now THOSE are tasty. I believe they are a variety of plum, because they have their own 'pit' in them. Kipawa is not interested in them at all - he walks right past the ones on the ground.