fishing cart
what kind of part is this? kind of like an internal lock washer?

My fishing cart wheel broke down, the part that cracked is almost like a 3/4 in internal toothed lock washer, but the teeth aren’t twisted, but are straight. What kind of part might that be called? My local ace hardware couldn’t id it.

I assume it’s the ring that held the cart wheel in place, while allowing its rotation around the fixed axle.
If so, the generic term is FORM or SHAFT RETAINER (RING), usually in elastic steel. They may be reused if carefully removed, but are best replaced with new.
For more detail, sizes etc. see the following supplier (one of many):

http://www.wclco.com/Lock_Washers/Shaft_Retainers.php

hth

Homemade Fishing Cart