My gorgeous mum's legacy

First, let me just say sorry for your loss.
With regard to the seeds, I have as yet no information on growing agapanthus from seed - hopefully someone else will give some info on this, but I will do a bit of research and get back to you if I find out anything useful.

If you google 'agapanthus seed propagation' you get loads of options for information, including one with the RHS - you might have to trawl through a bit, but I'm sure you'll find the answer you're looking for. Not sure what Hagborne is - I've heard of Headbourne hybrids.

I have an agapanthus in a large pot and some seed has fallen and germinated in the compost with no input from me . so yes they do germinate. as your seed is a little older you may find they are a bit stubborn. but i am sure your 'heritage' plants will bloom for you. what a lovely memory of your mum they will provide.