I have a very large framed (4'7"x 3'5") piece of southwestern (I think) piece of artwork. My uncle got it from a famous interior designer before he passed away. We think it may be worth something. The only information we have though is the it's a monotype, titled "indian Summer" signes James? Or Zames?

its is a picture of a 3 pots and what looks like an indian blanket in the background with some soft leaves falling arounfd the pots.

how do I find the artist and the value?

What was the name of the famous interior designer? Perhaps the interior designer specialized in recommending or supplying certain types of art to people that might be possible to be found in searches on the Internet or in books.

What I would suggest doing is taking the work of art to a college art professor, art gallery, or even an auctioneer for the identifying the artist. You also might find some monotypes listed in books at a public library with maybe even auction or sales prices listed. On the following searches, you might find items to be similar to the one that you have, and that might give you an idea as to how much monetary value something like this may have.

monotype eBay - Google Search

monoprint eBay - Google Search