The Edlin book that Andy mentioned is well worth looking out for. As is "The Identification Of Woods Used in Antique Furniture" by the ACC, this book has much larger wood samples, but is skewed towards antique timbers. Back in the day every veneer merchant and quite a few timber yards gave away sample sheets and blocks as per the photo below. I've still got quite a few, and it's astonishing how widely and consistently available many timbers used to be in both veneer and solid form. Not just exotics like Rio Rosewood or Burmese Teak, but European timbers like Yew, Pear, Sycamore, Sweet Chestnut, Elm, English Cherry, Apple, Hornbeam, Box, Laburnum, English Walnut, and many many others. You can still get them all today, but you really have to hunt to find them, and availability will be temporary and sporadic at best. Today's timber market, even by comparison to just twenty or thirty years ago, is a bit of a desert, we're now dominated by just six or seven hardwood species, and the majority of timber yards today will only ever stock this very limited range.
Two books that are absolute musts are The Handbook Of Hardwoods, sadly out of print but still widely available (get the latest version you can by the way, the one in the photo is the one to aim for, and also look out for it's "Softwoods" companion). And of course the Bruce Hoadley book. Hoadley is a fascinating read, but it's strongly biased towards the North American user, plus as a practical method of identification, the end grain shaving plus microscope route isn't going to be that viable for most people.
And if you've fallen deep into the "world woods" rabbit hole, then Adam Bowett's magisterial "Woods in British Furniture Making 1400-1900" is another must read.
However, fascinating as all these books are, as a practical method of identifying timbers none of them really cut it. There's so much variability within individual species that you need to look at scores or hundreds of different boards before you start to recognise the defining common characteristics. And photos or tiny samples can never really help you assimilate features like weight or fragrance or working qualities.
I thought the "lol" verdict on the £63 price for the timber collection was interesting. There was a similar thread about a year ago and I subsequently thought about offering something similar for sale, but when I realised I'd have to charge well over £100 per set (okay, I was planning on including some very rare items) and even then I wouldn't really be making much of a profit, I dropped the idea as a non starter. In a way that's a shame, as different temperate zone timbers drop off people's radar it'll become even easier for timber yards to feel there isn't the demand or need to broaden their product range.