My city has an environmental group that has been de-paving unused parking lots or a percentage of paved schoolyards to provide greenspace for vegetable gardens and Pollinator Gardens. They encourage residents to grow their own pollinator gardens in their yards and provide signs for those who do so.
Take a piece of 2x4 about 3 feet long and get your electric drill with a 7/32 inch bit and drill a couple hundred holes in the 2x4 then go hang it up under the eaves of a shed or outbuilding. The little wild bees will lay eggs in the holes and you will get loads of new bees right away.
Or, if you think you might enjoy keeping some honey bees, check this out: How To Keep Bees And Sell Honey: Walter T. Kelley
I have several hives but only take honey out of two on them. The rest are provide a place for bees to multiply. When I plant my cover crops it's always with the bees in mind. Lots of buckwheat, clover and field peas. I've even put up hives form the Mason bees, they do more pollination than honey bees after all.