You probably already know this but they're not really destructive like parrots, so toys can be hard to find for them.
I heard some peoples doves like preening toys, and the one time I accidentally left a piece of twine (similar to a preening toy) lying around near my pigeons one of the youngsters found it and started cooing at it and beaking it, so I guess he liked it aswell.
Foraging toys are usually a win, mostly trays rather than foraging toy balls or baskets, since they wont really sift through things in my experience. Also if you can find some fake grass and sprinkle seeds through it, mine love to ferret through the grass.
Also if yours like greens, giving them a whole leaf or even the whole plant and pegging it to the sides of the cage so they can peck at it and shred it is great enrichment.
Aww poor guy trying to court that ball. I find it interesting that each dove has a different courting coo.
Love the hops!!! The other year when there were a few youngsters all coming to my balcony for food, they would chase each other all over, hopping after each other It was the cutest thing ever