The Magic "Blanket".
Sometimes, a toddler can't sleep without their "special" thing.
Most children will find an object of comfort by the age of four. A blanket, a toy, a dummy. But here's a thing, even adults have an attachment object. A favourite jumper? Lucky underpants?

Comfort objects are a reminder of feeling calm, secure and being loved. This helps them to build feelings and confidence when they go out and discover the world.
Children keep experiencing and they know it: Parents can't at be there at all times to reassure them. But carrying an object that reminds them of that security creates a link between new experience and the comfort of home. So, when going to an unfamiliar place, they want to carry it with them?
From the classic blanket to the lego, these objects can provide them the security to a child throughout the night. So, when they wake up, they will reach for their security object. But that doesn't mean your child is feeling insecure. It's just an attachment to something to care.
It's also fine for children not to get attached to object. They may find other ways to self-soothe, sucking their thumb, touching their hair.
Oh...and the tragedy, the tragedy when you have to wash it...When you lose it. Let's leave him to choose a new one. But don't push your child to give it up. You will put more stress, like if the object is a bad thing. And there's nothing wrong about wanted to feel safe. Children leave it on their own when they no longer need it.
If you want your child to leave the "comfy object", you could try to set some new rules. The "blanket", the "teddy" is for home only...Let's not bring it outside, it will get dirty...
The object is the new link for home. You could also organise playdates and go to the playground. Children can meet, they will compare themselves and play together...Once children start preschool, they will see that other children don't carry a special object with them all the time. At this point, it's all about imitation and they'll usually give it up. It's the occasion to ask if your child will be ready to leave the object at home. It will be best if the suggestion's coming from the child.