we have the Wild flowers key by Francis Rose. it was recommend to us by our foraging guide. it's ok but, although it is very comprehensive, i've found it hard to work through (it might just be me). So i tried the Collins one, but it is so similar and no easier to use.
So still looking for a good guide to, especially with edibility in it (Mabey is ok, but there is way more out there than in his book).