A small book you can slip in your pocket to get started is the Collins series.
It'll just get you used to what's out there.
I think my next easy, cheap book to keep at home, was "A field guide in colour to wild flowers" with about 1,200 illustrations. It's layed out by the colour of the flowers & where they tend to grow. Nice to browse through, & start to notice which parts of the plants are used in identification, & their names. Also the latin names used, as well as the colloquial names. It's a good stepping stone if you get fascinated.
Neither of these books is by any means complete, but will keep you clear of seriously poisonous plants & you can take it as far as you wish.
If you get bitten by the bug - well my second hand "botany book" isn't complete either, & nearly 100 years old :shock: By that stage we're expected to know which family a plant belongs to eg. it's some sort of nettle. Then the precise one is identified by the description of the parts. (No nice piccies!:lol
You don't have to be a botanist to forage safely. My school friends & I were doing it from the age of 7 for our buns. I still stick to only about a dozen plants I use as forage.