I still get a little giddy when I pull an old copy off the shelf and find Tolkien’s own scrawl and sketches in it. If you want editions that actually reproduce J.R.R. Tolkien’s artwork, start with the original 1937 George Allen & Unwin publication of 'The Hobbit' — that first UK printing included his dust‑jacket design and a selection of his line drawings and maps. After that, many later Allen & Unwin and HarperCollins trade editions have kept reproductions of his colour plates and black‑and‑white drawings, though the exact contents vary by printing.
If you’re aiming for a single place that gathers most of his images, get hold of 'The Annotated Hobbit' by Douglas A. Anderson and the catalogue 'J.R.R. Tolkien: Artist and Illustrator' by Wayne Hammond and Christina Scull — both reproduce a wide range of Tolkien’s watercolours, ink drawings and maps. Also be aware that modern “illustrated” editions often feature new artwork by Alan Lee or John Howe; those are gorgeous but not Tolkien’s. I usually check the publisher notes and the contents list to make sure the edition actually says it contains ‘drawings by J.R.R. Tolkien’ before I buy, especially when I’m hunting for a bargain copy to read in the park.