Near Rhymes (similar sounds but not perfect):
* Market
* Starkest
* Barkus (made-up name)
* Caracas (city in Venezuela)
* Arkansas' (possessive form)
Eye Rhymes (spelled similarly but pronounced differently):
* Marcus
* Tarcus (made-up name)
Slant Rhymes (vaguely similar sounds):
* Darkness
* Sparkles
* Monarch
Rhymes using "Arkansas" as a word:
* "I'm going to Arkansas"
* "The state of Arkansas"
Ultimately, the best rhyme depends on your context and what sounds best to your ear.