"Skeleton rock buckets" can be found in various tine spacings.....google the name to find mfgrs. The closer the spacing, the smaller the rocks they can handle, but the more the tines plug in wet ground. As long as your hyd are good, you can flip those rocks in and shake dirt out, very easily. Check thickness and GRADE of steel- cheaper models wear down quickly and don"t let you dig bigger rocks out without damage.
One of the best machines I"ve ever bought. Too bad we didn"t have one when the kids were home, walking fields and picking by hand. At the time, they just appreciated the hyd dump wagon, instead of unloading by hand as well.