Well I don't think it will harm your frog.
but plain iceberg lettuce has very little nutrition and is mostly water.

Frogs will eat just about anything they can fit in their mouthes

I would stick to Dubia roaches , night crawlers , hornworms , once a month mice or rat if the frog is large enough.
Nothing wild caught as they have a higher chance of parasites.
No fish like gold fish. they are real bad news trust me.

I have heard of some keepers making their own food from sausage casings, dog food, beef heart , vitamins and calcium supplements.

Feel free to post pictures of your frog.
We love pictures.