Can I send gold and items to other players?

You can send resources (but not gold or other items) to alliance members after you unlock the trace center building (Around stronghold level 13)

Do though through the building or by tapping on the players base in the map and selecting 'Trade'.

Another way to get resources to another player is to empty all your troops from your estate (send them gathering or camp them) and let them attack you. If it is someone in your alliance then one of you would need to leave the alliance. They will also not be able to attack you if you are shielded. They will take all 4 resources until they reach the protection limits. Not as simple to control quantities but if it is large quantities it can be a lot faster than trading.