Hello Antonia, yes you can folllow legumes with legumes or lettuce with lettuce. Or you can do a two year rotation such as early broad beans, beetroot, early cabbage, leeks. Or you can grow without rotating, or rotate just a little…!
My asparagus has grown badly, I was too optimistic planting crowns on grass, should have folowed my own advice, also I have noticed slug damage to the few spears emerging, and they are hiding under cardboard! But if your soil is dry and the asparagus is established, you could use cardboard against the bindweed, although it will still creep out along the edges as quite a bit of light gets in that way.