use the capture filter  {not ether host 01:02:03:04:05:06}  where 01:02:... is your NIC's local MAC addr

You'll see all of the broadcast data.  Now, you can start filtering it out based on broadcast
method.  By doing this, you process one-by-one all possible methods of broadcasting/multicasting.

    !(ip.dst == 255.255.255.255)        [L3 broadcast]
    !(eth.dst == ff:ff:ff:ff:ff:ff)     [L2 broadcast]
    !(eth.dst[0:3] == 01:00:5e)         [multicast]
    !ipv6                               [ff02:* is multicast, however, I can't figure out how to get wireshark to filter on an ipv6 range, so it's all out for now)
    !llc                                [?]
    !lldp                               [link-layer discovery protocol]