This time of year, big green wrinkly apple like fruit. We always called them horse apples. Also, thorny branches. and once you cut into the heart wood, a bright yellow.
diameter, about 6" up, you want to find them think enough to split and let dry. Also, when you cut one, look for grain that is not very tight.
When to cut, winter is the best time for osage. Most other woods you want to cut in spring and no later than early summer.
Here are some staves seasoning.