I think this is the species observed within the shell of a pecan nut.
Hickory shuckworm moth, Cydia caryana
If interested, see my observation and iNat folks comments:
http://www.inaturalist.org/observations/2696277

This is, indeed, a caterpillar of a stored product pest moth. It is most likely Indianmeal moth (or Indian meal moth), as the caterpillars are fleshy colored without spots. The adults have forewings that are half tan and half copper-colored. The caterpillars infest a variety of dried goods, like almonds, noodles, rice, dog food, and bird seed. Infested goods will have silken strands or silken sheets as well as pellet droppings. The adult moth lives for about two weeks and does not eat or cause damage (it will drink water if available, though).

To stop the life cycle and thus the infestation, discard or freeze all infested goods and ensure noninfested goods are stored in airtight containers.

Not all beetles will have C-shaped larvae, but weevils generally do. If your larva has three pairs of legs near the head and little stumpy "false legs" (prolegs) down the rest of the body, you are dealing with a larval Lepidopteran.

Fly larva = maggot = no legs
Beetle larva = grub = six legs
Moth or butterfly larva = caterpillar = six legs near head and several pairs of prolegs