Anyway here's some primitive or crab apples. First up is Malus "Golden Hornet" which has featured here before.
That's an asparagus bed and an out of control spaghetti squash in front btw and the super-rare Katsura tree morph Cercidiphyllum japonicum 'Heronswood Globe' peeking out back. It's worth noting yellow crab apples (and indeed yellow forms of most berries/fruit) will often get left by the birds til last for some reason.
The fruit above is on a tree which is also supposed to be Golden Hornet-esque but as you can see it's rather different. This was grown from seed from a Golden Hornet plant the owner believed to be reproductively isolated but which it seems wasn't. I suspect there is an eating apple of some sort in there somewhere. On a good year it produces lots of creamy yellow fruits which are best described as "giant crab apples" (ie still well short of anything like a decent sized apple). It's rather beautiful and some day I think I might propagate it to share with the world under a corny name (perhaps it will make me rich!).
Above and below are both Malus hupehensis I think (literally the "Apple from Hupeh province in China"). These will ripen to a much deeper red and are absolutely beloved of birds.
Next up "Proper" apples and then some weirder stuff.