why not run a carnival, have raffles, get some local merchants to donate some stuff, get some local entertainment to perform for charity/exposure.The town donated a portable stage(trailer with a stage built in) for people to sing and entertain.
Make a nice set of outdoor furniture and and donate it so they can raffle it off.
whatever is fun, hayrides, pony rides, pie eating contests, hot dog eating contests, get people invovled and willing to part with a few bucks for the good of the town park.
I donated a pair of adirondack chairs to a local pta to raise funds, and was told they did well with just those.
They had some of the fathers and custodians running a bbq with hotdogs and burgers and the line was long from late morning till it closed.They sold ice cream, cotton candy, pretzels, etc...they had boths for just kids, like sand art.
I dont know if this is big enough stuff for your local park. It worked well for the pta.