| I would expect that it is a Hawthorn (Crataegus species), a member of the rose family. There are MANY types and very popular with wildlife. |
Here is a link that might be useful: Crataegus in the US distribution
| Not sure if this is considered to be in the Hawthorn family or not, but quince also has small apple like fruit that is very bitter. |
Here is a link that might be useful: Quince
| Or, it could be flowering quince, Chaenomeles japonica or C.speciosa. |
Here is a link that might be useful: Chaenomeles