The 11th edition of La Foire à la Bouture de Couture sur Loir (41800) on 23rd October sounds really interesting.
Free of charge, the event is an venue to exchange plants, cutting and seeds and to swap gardening experiences.
There are a couple of conferences, one on herbacious plants and the other on insects and at least one nursery will be selling their wares, but otherwise is seems to be a delightfully chaotic amateur affair in the best possible atmosphere.
I shall try to go.