Nightscape Press has several open submission calls for a short story anthology, a Best of New Weird 2018 Anthology, and the Nightscape Charity Line. Payment is different for each open call, as are open and close dates. Full details are found here. 

Paper Butterfly Flash fiction is open to flash stories of up to 1,000 words, from any genre, until April 30, 2019. Payment is a flat $10 CD. Full details are found here.