Your bedroom is a good place to practise counting forwards and backwards with your toys. Can they line up for you to count them? What happens if you take one away, or add one? Ten in a Bed is a great song to practise this.
In EYFS we learn how to share. Not only as a way of making friends but also as an important maths concept. Can you choose some of your toys from your bedroom and share them fairly between you and your siblings or the grown ups in your house. Can you make it a fair share? Are the groups equal? What happens if there is one left over? When we do a fair share between two people it is called halving. You could explore this in lots of ways with the toys or any items in your bedroom. Learning to share is very important!