It is believed the items, which include a hand painted stone squirrel and a wooden hen, were stolen and then left in the garden on Dowber Way as a prank, sometime overnight between Sunday 11 March and Monday 12 March 2012.
As well as the stone squirrel and the wooden hen, a black metal cockerel weather vane and a solar powered garden light were also left behind.
Officers have been making local enquiries in an effort to find out who the items belong to and are urging the owners to come forward.
PC Duncan Pears, of Thirsk Safer Neighbourhood Team, said:
Although we think the items were left in the garden as a prank, they must have been taken from somewhere and someone must be missing them.
If you think the items belong to you, they are currently in the possession of the police, so please get in touch and we will arrange for you to have them back.
I would also appeal to anyone who saw any suspicious activity in the area at the time of the incident to contact the police or Crimestoppers with information.
If the items are yours or if you can help the investigation please contact North Yorkshire Police on 101 – select option 2 – and ask for Duncan Pears or Thirsk police.
Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.