Things:
* table
* television
* toothbrush
* toy
* tree
* towel
* train
* truck
Places:
* town
* tower
* tunnel
* tent
People:
* teacher
* teenager
* thief
* tourist
Animals:
* tiger
* turtle
* toad
* turkey
Concepts:
* time
* truth
* talent
* technology
* tradition
Food & Drink:
* tea
* toast
* tomato
* taco
* tuna
Other:
* tool
* thread
* thumb
* thought
* treasure
* temperature
* team
* test
This is just a small sample, and there are many more common nouns starting with "t"!