Here are a few simple questions to ask that will help you identify a bird's nest based on where you are and what it looks like.
British Bird Egg Identification Chart - The Bird House
Birds and their nests - Local Land Services
Nest and Egg Identification Resources - The Infinite Spider
How to Identify Common Wild Backyard Bird Eggs
Western Birds' Nests + Eastern Birds' Nests – Cool Tools
Empty Bird Nests: 7 to Identify in the Garden - Woodland Trust
How to identify bird and mammal nests - Discover Wildlife
Bird Nest Identification: 5 QUICK Ways! (Read THIS First!) - Birding Outdoors
A Year & A Day Magazine Issue 1 Eggs, Birds and Nests - Honeybee Toys
The NHBS Guide to UK Bird Nest Identification
Beginner's Tips For Identifying Backyard Bird Nests
9 Different Types of Bird Nests and How to Spot Them - Birds and Blooms