Is there a stone fruit tree someone could recommend for northeast Indiana? I have a half acre backyard and want to cut down on space and maybe grow something for the farmer's market.
In Northeast Indiana, you're in zone 5. There should actually be quite a lot of stone fruit trees that do well for you, depending on your soil. Stone fruit trees tend to be short-lived in our climate. In my opinion, they're still worth trying.
Sour cherries should do very well for you. Montmorency is an easy one to find that does well in zone 5, but North Star is also an excellent one - very hardy and a heavy, consistent producer with good flavor.
Conventional wisdom is that sweet cherries do not do well in the Great Lakes region, but I've had good luck with a Stella Compact that I've had for almost 10 years now. It is a self-fertile, dwarf sweet cherry. Self-fertile is important because few people around here attempt sweet cherries, so fertilization can be an issue if you only want to plant one tree.
Plums do fairly well here, but are susceptible to borers. Mount Royal and Stanley should be easy to find for dark plums. Toka is a hardy red plum that also shows up at a lot of nurseries around here.
If you want peaches, go with Reliance or Madison. I have a Reliance, and when I get peaches off of it, they are certainly better than store peaches, but not as good as the peaches you get off of the fruit trucks that come up from down south. It is not a reliable cropper - I get fruit every two years if I am lucky. It tends to have some die-back that needs to be cut out ever year. Also, the Japanese beetles love the fruit, so I have to cut away beetle damage to eat them. If you have a extra space and want to try a peach tree as a novelty, go for it. I wouldn't recommend a peach otherwise, though.
Fruiting cherry should work, but unfortunately, because you're in the North East, it won't be sweet cherries, it'll have to be the tart type, because of the vagaries of your weather there - more info in the link below
Peaches might work, depends which USDA zone you're classed as there - they work best in Zones 6 and 7, but will grow in zone 5, see link
It's probably worth consulting a specialist fruit tree seller in the area, because some varieties of peach are hardier than others - there are likely also some plum varieties that will do well in your region. Stark Brothers has one called Stanley Prune-Plum which is recommended for Zones 5-7, for instance. http://www.starkbros.com/products/fruit-trees/plum-trees/stanley-prune-plum
The link below gives broad, general information about trees for Indiana which might be of interest
There are other factors to consider though - your soil type and exposure will make a difference to what you can successfully grow.