Greetings Dee:
These small diameter logs are too "small" to sell to a local sawmill. However, you may garner some interest from local woodworking clubs. Larger, quality black walnut logs with a minimum diameter inside bark (DIB) at the small end of 17" may go for $0.80-2.25/board foot. Please note, this is simply a range as there certainly other factors to consider: volume, log length, quality, external/internal defects, etc.
Check with your local woodworking cooperatives to see if anyone is interested in purchasing these logs. Otherwise, they are simply too small to market as sawlogs.